TN295 



No. 8962 





ISJuIT 



IC 


8962 



Bureau of Mines Information Circular/1983 




Lead and Zinc Availability— Domestic 

A Minerals Availability Program Appraisal 

By Catherine C. Kilgore, Sylvia J. Arbelbide, and Audrey A. Soja 




UNITED STATES DEPARTMENT OF THE INTERIOR 



(VLrJLfeA JittX&y. PMjteau f/ Ihstet 



Information Circular 8962 



Lead and Zinc Availability— Domestic 

A Minerals Availability Program Appraisal 

By Catherine C. Kilgore, Sylvia J. Arbelbide, and Audrey A. Soja 




UNITED STATES DEPARTMENT OF THE INTERIOR 
William P. Clark, Secretary 

BUREAU OF MINES 
Robert C. Horton, Director 






«1' 

As the Nation's principal conservation agency, the Department of the Interior 
has responsibility for most of our nationally owned public lands and natural 
resources. This includes fostering the wisest use of our land and water re- 
sources, protecting our fish and wildlife, preserving the environmental and 
cultural values of our national parks and historical places, and providing for 
the enjoyment of life through outdoor recreation. The Department assesses 
our energy and mineral resources and works to assure that their development is 
in the best interests of all our people. The Department also has a major re- 
sponsibility for American Indian reservation communities and for people who 
live in Island Territories under U.S. administration. 



Library of Congress Cataloging in Publication Data: 



Kilgore, Catherine C 

Lead and zinc availability —domestic. 

(Information circular ; 8962) 

Bibliography: p. 25 

Supt. of Docs, no.: I 28.27: 8962. 

1. Lead ores— United States. 2. Zinc ores— United States. 3. 
Lead industry and trade— United States. 4. Zinc industry and trade — 
United States. I. Arbelbide, S. J. (Sylvia J.). II. Soja, A. A. (Audrey 
A.). III. Title. IV. Series: Information circular (United States. Bu- 
reau of Mines) ; 8962. 

TN295.U4 [TN453.A5] 622 [553.4M'0973] 83-600311 



For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 



PREFACE 

The Bureau of Mines Minerals Availability Program is assessing the worldwide 
availability of nonfuel minerals. It identifies, collects, compiles, and evaluates information 
on active and developing mines, explored deposits, and mineral processing plants 
worldwide. Objectives are to classify domestic and foreign resources; to identify, by cost 
evaluation, resources that are reserves; and to prepare analyses of mineral availabilities. 

This report is part of a continuing series of reports that analyze the availability of 
minerals from domestic and foreign sources and the factors affecting availability. Ques- 
tions about these reports should be addressed to Chief, Division of Minerals Availability, 
Bureau of Mines, 2401 E St., NW., Washington, DC 20241. 



-4 



CONTENTS 



Page 

Preface iii 

Abstract 1 

Introduction 2 

Methodology 2 

Domestic lead and zinc industry 3 

Domestic lead industry 3 

Secondary production of lead 3 

Domestic zinc industry 4 

Closures in lead and zinc industry 4 

Domestic resources 5 

Primary lead resources 5 

Domestic lead capacity 5 

Primary zinc resources 7 

Domestic zinc capacity 9 

Summary of domestic resources 9 

General geology 10 

Deposit type and relationship to byproduct content . 10 

Mining methods and costs 12 

Room-and-pillar methods 12 

Room-and-pillar with sublevel stoping methods . . 13 

Room-and-pillar with shrinkage stoping methods . 14 

Backfill methods 14 

Open pit methods 14 

Milling methods and costs 14 

Postmill costs 14 

Transportation 15 



Page 

Postmill processing contract terms 15 

Operating costs 16 

Capital costs 17 

Availability of domestic resources 18 

Primary lead 18 

Primary zinc 18 

Sensitivity analyses 19 

Impact of varying discounted-cash-flow rate of 

return 19 

Impact of byproduct price changes 20 

Impact of increased postmill processing 

charges 21 

Summary of sensitivity analyses 22 

Summary 23 

Deposit classifications 23 

Primary lead 23 

Sensitivity analyses results for primary lead .... 23 

Primary zinc 23 

Sensitivity analyses results for primary zinc .... 24 

Domestic smelter capacity 24 

References 25 

Appendix A.— Domestic lead and zinc ownership 

information 26 

Appendix B.— Mines and deposits excluded from 

this study 26 

Appendix C— Geology narratives by State 27 



ILLUSTRATIONS 

1 . Locations of primary lead mines and deposits 5 

2. Locations of primary zinc mines and deposits 6 

3. Locations of smelter and refinery facilities utilized 7 

4. Relationship between mining methods and deposit classification 13 

5. Breakdown of mining methods by primary commodity 13 

6. Byproduct revenues and operating costs per pound of primary lead or zinc recovered at each operation . . . 

7. Cost and total availability of primary lead 18 

8. Cost and annual availability of primary lead for selected years 18 

9. Annual availability of producing primary lead operations for selected price ranges 18 

10. Cost and total availability of primary zinc 19 

1 1 . Cost and annual availability of producing primary zinc operations for selected years 19 

12. Cost and annual availability of nonproducing primary zinc operations for selected years 19 

1 3. Cost and total availability of primary lead at 0- and 15-pct DCFROR 20 

14. Cost and total availability of primary zinc at 0- and 15-pct DCFROR 20 

15. Cost and total availability of primary zinc using average 1980 and January 1982 commodity prices 20 

16. Cost and total availability of primary lead using average 1980 and January 1982 commodity prices 21 

17. Primary lead byproduct revenues below $3.50 per pound of recovered lead, for selected operations, at 

average 1980 and January 1982 commodity prices 21 

18. Primary zinc byproduct revenues below $3.50 per pound of recovered zinc, for selected operations, at 

average 1980 and January 1982 commodity prices 21 

19. Cost and total availability of primary lead using the study value and 50 pet higher smelter treatment charges 22 

20. Cost and total availability of primary zinc using the study value and 50 pet higher smelter treatment charges 22 

C-1 . Locations of lead operations in the Viburnum Trend in Missouri 28 

C-2. Locations of zinc operations in Tennessee and Kentucky 29 



TABLES 



1 . Commodity prices used in economic evaluations 3 

2. Historic production of lead 3 

3. Zinc import, export, and consumption figures for the years 1980 and 1981 4 

4. Demonstrated resources for primary lead mines and deposits 6 

5. Summary of demonstrated resources values for domestic lead 6 

6. Demonstrated resources for primary zinc mines and deposits 8 

7. Summary of demonstrated resources values for domestic zinc 9 

8. Comparison of Crandon and Red Dog deposits' resource values with total primary zinc resource values ... 9 

9. Non-Mississippi-Valley-type deposits 10 



Page 

10. Commodities recovered as byproducts at primary lead properties 11 

1 1 . Commodities recovered as byproducts at primary zinc properties 11 

12. Mining methods used or proposed for primary lead operations 12 

13. Mining methods used or proposed for primary zinc operations 12 

14. Selected mine operating costs 13 

15. Smelter schedule developed for domestic lead and zinc and copper concentrates 15 

16. Application of the generalized smelter schedule 16 

17. Breakdown of operating costs showing the number of operations in each percentage category 16 

18. Commodity prices used in byproduct sensitivity analyses 20 

19. Weighted average of total cost of production for primary lead operations 22 

20. Weighted average of total cost of production for primary zinc operations 22 

A-1 . Domestic lead ownership information 26 

A-2. Domestic zinc ownership information 26 

C-1 . Primary zinc operations in Tennessee and Kentucky 29 



UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT 



km 


kilometer 


t 


metric ton 


lb 


pound 


t/yr 


metric ton per year 


Itu 


long ton unit 


ton 


short ton 


Ib/t 


pound per metric ton 


ton/t 


short ton per metric ton 


m 


meter 


tr oz 


troy ounce 


tr oz/ton 


troy ounce per short ton 


wt pet 


weight percent 


pet 


percent 


y 


year 


sq km 


square kilometer 







LEAD AND ZINC AVAILABILITY— DOMESTIC 
A Minerals Availability Program Appraisal 

By Catherine C. Kilgore, 1 Sylvia J. Arbelbide, 1 and Audrey A. Soja 2 



ABSTRACT 



The Bureau of Mines investigated the availability of lead and zinc from 104 domestic 
mines and deposits. Fourteen primary lead and fifty-three primary zinc operations with 
in situ demonstrated resources containing 27.3 million metric tons (t) of lead and 53 million 
t of zinc were subsequently evaluated. 

Potentially 17.5 million t of lead and 2.4 million t of byproduct zinc could be recovered 
from 14 primary lead operations. Economic evaluations performed in constant January 
1982 dollars determined a long-run total cost per pound of recoverable commodity. In- 
cluding a 15-pct discounted-cash-flow rate of return (DCFROR), 59 pet of primary lead 
was potentially available at or below $0.32 per pound of lead. 

Potentially 40 million t of zinc and 5.6 million t of byproduct lead could be recovered 
from 53 primary zinc operations. Ninety percent of the recoverable zinc is potentially 
available from currently nonproducing mines and deposits, and a weighted average of 
their long-run total costs was determined at $0.98 per pound of zinc. At a breakeven (0-pct) 
DCFROR, these nonproducing operations had a weighted average long-run total cost of 
$0.58 per pound of zinc. 

Sensitivity analyses illustrated that operations that recover byproducts were most sen- 
sitive to fluctuating metal prices, producing operations were more sensitive to increased 
smelter treatment charges, and nonproducing operations were impacted most by the 
DCFROR. 

'Geologist 
^Economist. 
Minerals Avajlatxiity Field Office. Bureau of Mines, Denver, CO. 



INTRODUCTION 



The purpose of this report is to identify and define the 
demonstrated domestic lead and zinc resources and evaluate 
the potential production from these resources. The Bureau 
investigated the availability of lead and zinc from 104 
domestic mines and deposits, and subsequently evaluated 
the engineering and economic availability of lead and zinc 
from 67 of the mines and deposits. A complete listing of the 
67 mines and deposits that were evaluated and their owner- 
ship is given in appendix A. 

The procedure for this evaluation was to identify 
recoverable resources and the engineering and economic 
parameters that would affect proposed production from the 
deposits selected for evaluation. Capital investments and 
operating costs (direct and indirect) for the appropriate min- 
ing and beneficiation methods were estimated, transporta- 
tion costs and standardized postmill processing charges were 
assessed, and a cost evaluation for each deposit was per- 
formed. Finally, the individual deposit evaluations were ag- 
gregated to show potential lead and zinc availability at various 
commodity prices. 

Of the initial 104 deposits investigated, 37 were excluded 
from evaluation because their resource tonnages were 
reported as inferred rather than demonstrated, or because 
the demonstrated resources as of January 1 , 1981 , contained 



less than 50,000 1 of in situ primary lead or zinc. 3 Deposits 
excluded from evaluation are listed in appendix B. 

The top 15 domestic producers of lead and/or zinc in 
1981 were included in this evaluation with the exception of 
the Austinville and Ivanhoe mines in Virginia, which are near 
depletion (f-2). 4 As of the 1982 evaluation date, there were 
five producing mines with demonstrated resources contain- 
ing less than 50,000 1 of in situ lead or zinc that were included 
because their resources were not near depletion. Three of 
these mines were included because they have small annual 
production rates and estimated production lives of nearly 20 
yr. The other two operations have historically estimated close 
to the same resource tonnage every year. Mines such as 
these two, with small resource tonnages for lead and zinc, 
may produce precious metals as their primary product, but 
also produce significant quantities of lead and/or zinc. These 
mines may define a resource tonnage sufficient for only a 
few years of production at current mining rates for various 
reasons, such as complex geological conditions and high ex- 
ploration costs. 

The methodologies employed to define and evaluate 
engineering and economic parameters for each individual 
mine or deposit are described in the following section. 



METHODOLOGY 



The Minerals Availability Program is developing a con- 
tinuously evolving methodology for the analysis of long-run 
mineral resource availability. An integral part of this system 
is the Bureau's Supply Analysis Model (SAM) (3). This interac- 
tive computer system is an effective mathematical tool for 
analyzing the effects of various parameters upon the 
economic availability of domestic and international resources. 

For each operation included in this evaluation, capital 
expenditures were calculated for exploration, acquisition, 
development, mine and plant equipment, and for construc- 
ting and equipping the mill. The capital expenditures for the 
different mining and processing facilities include the costs 
of mobile and stationary equipment, construction, engineer- 
ing, infrastructure, and working capital. Infrastructure is a 
broad category that includes costs for access and haulage 
facilities, ports, water facilities, power supply, and person- 
nel accommodations. Working capital is a revolving cash fund 
required for operating expenses such as labor, supplies, in- 
surance, and taxes. 

The initial capital costs for producing or past producing 
mines and developed deposits have been depreciated ac- 
cording to when the investment was actually made, and the 
undepreciated portion was treated as a capital investment 
in 1982, the first year of the evaluation. Reinvestments will 
vary according to capacity, length of production life, and age 
of the facilities. 

The total operating cost of a mining project is a combina- 
tion of direct and indirect costs. Direct operating costs include 
operating and maintenance labor and supplies, supervision, 
payroll overhead, insurance, local taxation, and utilities. The 
indirect operating costs include technical and clerical labor, 
administrative costs, maintenance of facilities, and research. 

After production parameters and costs for the develop- 
ment of domestic lead and zinc deposits were established, 
the SAM was used to perform various economic evaluations 
pertaining to the availability of domestic lead and zinc. The 
SAM system is a comprehensive economic evaluation 
simulator that is used to determine the constant-dollar long- 
run price at which the primary commodity must be sold (after 
smelting-refining) to recover all costs of production, including 
a prespecified discounted-cash-flow rate of return (DCFROR) 



on investment. The DCFROR is defined as the rate that 
makes the present value of all current and future revenues 
equal to the present value of all current and future costs of 
production. For this study, a constant rate of return on in- 
vestment of 15 pet was specified. This rate was considered 
sufficient to attract new capital to the industry. 

The SAM system contains a separate tax records file for 
each State, which includes all the relevant tax parameters 
under which a mining firm would operate. These tax 
parameters are applied to each mineral deposit under evalua- 
tion with the implicit assumption that each deposit represents 
a separate corporate entity. Other costs in the analysis in- 
clude standard deductibles such as depreciation, depletion, 
deferred expenses, investment tax credits, and tax loss carry 
forwards. The SAM system also contains a separate file of 
economic indexes to allow for updating of all cost estimates 
for both producing and nonproducing deposits. 

Price tables are maintained for all primary commodities, 
byproducts, and coproducts that will be relevant to the 
availability analyses, and all byproducts recovered in the 
analyses are considered to be marketable. The commodity 
prices used in this study are shown in table 1 . 

Detailed cash-flow analyses are generated with the SAM 
system for each preproduction and production year of a mine 
or deposit beginning with the initial year of analysis, 1982. 
Upon completion of the individual analysis for each deposit, 
all properties were simultaneously analyzed and aggregated 
into an availability curve. 

The availability of the primary product recoverable from 
a deposit is presented graphically, and in the text of this 
evaluation, as a function of the total cost of production 
associated with that deposit. Availability curves are con- 



3 The term "contained" refers to the actual quantity of the element present 
within the ore, concentrate, or final product, irrespective of its form. The term 
"in situ" denotes resources existing in the ground. Thus, the mines or deposits 
excluded from this study contained less than 50,000 1 of the element in various 
mineral forms in demonstrated resources. In situ grade refers to the percent- 
age of lead or zinc contained in the deposit. Demonstrated and inferred 
resources are defined in the "Domestic Resources" section. 

■•Italicized numbers in parentheses refer to items in the list of references 
preceding the appendixes. 



Table 1. — Commodity prices used in economic evaluations 



Commodity 

Barite per ton 

Cadmium per lb 

Copper per lb 

Fluorspar per I 

Gold per tr oz 

Iron (pellets) per Itu 

Lead per lb 

Limestone per t 

Silver per tr 02 

Zinc. . . . per lb 



Price. 
January 1982 

$105.00 

1 40 

79 

165 00 

384 12 

81 

.30 

4.13 

803 

.42 



structed as aggregations of the total amount of commodity 
potentially available from each of the evaluated operations, 
ordered from the deposits having the lowest average total 
cost per unit of production to those having the highest. The 



potential availability of the primary commodity at a price can 
be seen by comparing, for example, the expected long-run 
constant-dollar market price to the average total cost values 
shown on the availability curves. The total recoverable ton- 
nage potentially available at or below this price-cost value 
can be read directly from the total availability curve. Annual 
availability curves were also constructed to account for the 
time lags involved in achieving the total production poten- 
tial. These curves are simply the total availability of domestic 
lead or zinc in any given year, based on the development 
and production schedules assumed for each deposit. 

Certain assumptions are inherent in these curves. First, 
all deposits will produce at full design capacity throughout 
the productive life of the deposit. Second, each operation will 
be able to sell all of its output at the determined total cost 
and obtain at least the minimum specified rate of return. Third, 
all preproduction development of all nonproducing deposits 
began in January 1982. 



DOMESTIC LEAD AND ZINC INDUSTRY 



The availability of domestic lead and zinc as presented 
in this report is affected by a number of factors currently in- 
fluencing the lead and zinc industries in general. A brief over- 
view of the domestic industry is presented in this section. 



DOMESTIC LEAD INDUSTRY 

The United States is the largest refiner and consumer 
of lead in the world. Average primary (refined) production of 
lead between 1977 and 1981 was reported at 549,000 t/yr, 
and average domestic mine production levels over the same 
period were reported at 94 pet of this level, 518,000 1 of con- 
tained lead per year (2). Many of the domestic lead mines 
produce competitively in the world market, particularly the 
highly mechanized Missouri operations, which produce most 
of the domestic concentrates. However, the United States 
is still a net importer of lead concentrates and refined lead, 
and average consumption levels between 1977 and 1981 of 
nearly 1 .3 million t of contained lead in all forms have resulted 
in an average net import reliance of about 4 pet (4-5). 

The cost of meeting environmental regulations may have 
been a significant factor in recent closures of domestic 
smelter facilities for both primary and secondary lead. Major 
capital expenditures have been required for most producers 
to attempt to meet the regulations of the Clean Air and Clean 
Water Acts, as well as the numerous regulations promulgated 
by the Occupational Safety and Health Administration 
(OSHA). Some of the facilities have closed down temporar- 
ily, or even permanently, because they cannot meet the 
numerous regulations, and heavy fines are often imposed for 
violations (&&). 



Secondary producers compete with primary producers 
because refined secondary lead may be substituted com- 
pletely for primary lead in most applications. Technically, 58 
pet of all primary lead produced may potentially be recycled 
(6). The similarity of the two products allows for a high degree 
of competition in determining the level of the U.S. producer 
price for lead. 

The recent trend of low primary producer prices effec- 
tively narrowed the gap between primary and secondary pro- 
ducer prices and cut into the profit margins of secondary pro- 
ducers. With the relatively high scrap prices, production levels 
have declined, resulting in excess processing capacity. The 
industry estimates that between 70 and 75 pet of the 
1.1-million-t/yr secondary scrap capacity is currently being 
utilized (6). 

Although there is sufficient domestic smelting capacity 
available, the United States is a large exporter of scrap lead 
for the secondary production industry. Foreign secondary 
smelters have been outbidding U.S. smelters for the lead 
scrap in recent years, due in part to higher capital, operating, 
and environmental costs borne by the domestic smelters. 
There have been no long-term, industry-wide, physical raw 
material shortages, however. If all U.S. -generated scrap were 
recycled domestically, refined imports could potentially be 
halved and U.S. self-sufficiency could approach 100 pet (7). 

As illustrated in table 2, total domestic production of 
secondary lead is greater than primary mine production. 
However, since 1979, secondary lead production levels have 
dropped as a number of economic difficulties have plagued 
the secondary lead industry. The most significant difficulty 
is the continuing shortage of available scrap at acceptable 
prices. 



SECONDARY PRODUCTION OF LEAD 

The United States has a well-developed secondary metal 
industry that included about 58 major operating plants in 
1 981 . These plants recovered approximately 641 ,000 1 of con- 
tained lead from scrap, which represented 55 pet of total 
reported lead consumption. Between 1977 and 1981, second- 
ary production of lead from scrap has averaged 729,000 t/yr, 
representing 56 pet of reported consumption (2). 

With consumption declining in dissipative uses such a 
tetraethyl lead (TEL) in gasoline, more lead may be consumed 
in products that are easily recyclable and, as a result, scrap 
lead could become more readily available and provide a 
strong incentive for increased secondary production (5). The 
secondary lead industry currently depends heavily on the bat- 
tery industry as both a source of feed and as a market outlet. 



Table. 2. — Historic production of lead 

(Thousand metric tons of contained lead) 

Production 1977 1978 1979 1980 1981 

Mine 537 530 526 550 446 

Primary (refined)' 552 568 578 548 498 

Secondary 758 769 801 676 641 

Secondary, percent of total 
contained lead from 
primary and secondary 
production 58 57 58 55 56 

' Refined lead plus lead content of antimomal lead, and foreign ores imported 
for consumption 

Source Reference 2. 



DOMESTIC ZINC INDUSTRY 

Domestic zinc mine-mill capacity has declined over the 
years, and the U.S. share of concentrate production in the 
world market has fallen to barely 5 pet (1). The declining im- 
portance of the domestic zinc mining industry results in part 
from low ore grades and low byproduct revenues from many 
domestic zinc operations, which result in some of the highest 
production costs in the world (7). 

The number of domestic zinc postmill processing 
closures over the years has resulted in a drop in self- 
sufficiency in metal production, and an increase in the 
domestic reliance on imported zinc products. Foreign govern- 
ment aid programs that stimulate smelter construction have 
resulted in severe competition from foreign smelters, and the 
trend towards importing refined products has grown over the 
years (7-8). 

Environmental costs have only been one of several fac- 
tors contributing to recent closures in the zinc industry. Out- 
moded technology, lack of feed sources, and the high cost 
of energy and labor have also impacted the domestic industry. 
Smelter facilities built in the early 1900's have predominated 
the domestic industry, and a number of them have required 
extensive modernization, or complete replacement in recent 
years. Along with the high cost of operating and/or modern- 
izing the older, and often energy-intensive smelter facilities, 
the relatively low domestic zinc grades and resulting decline 
in production have had the greatest negative economic im- 
pact on the domestic zinc industry (7-9). 

Mine production rates for zinc between 1977 and 1981 
have averaged 321 ,000 t/yr, while apparent domestic con- 
sumption levels have been significantly larger, at 1 .3 million 
t/yr of contained zinc in all usage forms (1). This difference 
has resulted in an average net import reliance of 62 pet dur- 
ing this period (10-11). 

Table 3 lists the imports, exports, and consumption levels 
for various forms of zinc for 1980 and 1981 . As shown in the 
table, the United States imported nearly twice as much zinc 
metal in the form of blocks, pigs, and slab as in zinc ore and 
concentrate. Imports of zinc ore and concentrates were 
mainly from Canada, Peru, Mexico, and Honduras. Primary 
suppliers of the metal products were Canada, Spain, Mex- 
ico, Australia, Peru, Finland, and Zaire. 



CLOSURES IN LEAD AND ZINC INDUSTRY 

As the recent trend of increasing production costs and 
declining metal prices continued, domestic mine production 
also declined. Domestic smelters and refineries have had to 
buy foreign concentrates in order to keep operating, as the 
trend of reduced domestic concentrate production, parti- 
cularly zinc, has continued (8). Operations in many countries 
are able to produce and export the final products, such as 
slab zinc, at prices below their U.S. counterparts, who have 
to add the cost of importing foreign concentrates to their cost 
of processing. The shortage of domestic zinc concentrates, 
along with the already high capital and operating costs that 
plague the domestic smelters and refineries, have resulted 
in a number of cutbacks in production and permanent 
closures in the industry. 

The Bunker Hill lead-zinc-silver mining and metallurgical 
complex in Kellogg, ID, closed at the end of 1981, typified 
the problems facing the domestic industry. The Bunker Hill 
smelter and refinery operations annually accounted for ap- 
proximately 1 1 3,000 1 of primary lead and 91 ,000 1 of refined 
zinc, and in 1980 its production represented 20 and 21 pet 
of the domestic refined lead and zinc, respectively (8). In ad- 
dition, the Bunker Hill facilities annually produced between 



Table 3.— Zinc import, export, and consumption figures for the 
years 1980 and 1981 

(Thousand metric tons of contained zinc) 

1980 1981 

Imports: 
Ore and concentrates: 

Canada 110 180 

Honduras 7 4 

Mexico 14 21 

Peru 40 29 

Other 11 12 

Total 182 246 

Metal (blocks, pigs, slab): 

Australia 25 26 

Canada 280 309 

Finland 18 29 

Mexico 24 15 

Peru 4 43 

Spain 11 29 

Zaire NAp 29 

Other 48 132 

Total 410 612 

Exports: 

Slab .3 .3 

Waste and scrap 30 30 

Ore and concentrate 54 54 

Total 84 85 

Apparent consumption: 

Slab 811 834 

Ores 59 61 

Zinc scrap 133 149 

Other scrap 1 139 139 

Total 1,142 1,184 

NAp Not applicable. 

' Other scrap includes zinc contained in copper, aluminum, and magnesia- 
based scrap. 

NOTE. — Data may not add to totals shown because of independent rounding. 
Source: Reference 1. 



1 and 1 2 million tr oz of silver (23 pet of the domestic primary 
silver output for 1980), over 1 million lb of cadmium, and a 
variety of other byproducts. A portion of these metals were 
derived from Bunker Hill's own mines; however, portions of 
the output were derived from concentrates purchased from 
or tolled for other parties, both domestic and foreign (8, 12). 
Bunker Hill has cited labor disputes, low metals prices, and 
environmental costs as reasons for its closure (13). 

The Bunker Hill smelter and refinery facilities have not 
been dismantled to date, and it could resume operation with 
minimum capital expenditures, possibly in less than a year. 
For these reasons, the capacity is considered to be on a 
standby basis and is potentially available if needed. However, 
the facility was closed as of the study date and not utilized 
for this evaluation. 

Although many mines and smelting and refining opera- 
tions have announced plans to cut back on production or 
close indefinitely, changes in the economy, particularly im- 
provements in metals prices, could provide the incentive to 
bring a number of them back into operation. As mining opera- 
tions return to or increase production, or as new operations 
start, the smelting industry could also begin to pick up. For 
example, in 1979 the Monaca zinc plant in Pennsylvania was 
closed indefinitely (14). However, bringing the new Pierre- 
pont deposit into production in 1982 supplied the ore con- 
centrates and the incentive to initiate the $2 million reactiva- 
tion of the Monaca plant (15-16). 



DOMESTIC RESOURCES 



Selection of mines and deposits for this study was limited 
to known deposits with demonstrated lead and zinc resources 
containing at least 50,000 t of in situ primary lead or zinc. 
Demonstrated resources are defined as the measured plus 
indicated portion of identified tonnages (17). The in situ con- 
tained lead and zinc values are derived from these tonnages. 
For this evaluation, demonstrated resources are not restricted 
by economic status and may include resources that are cur- 
rently economic, marginally economic, and even 
subeconomic. 

As mentioned previously, 37 of the 104 mines and 
deposits originally analyzed were excluded from this study 
because their resource tonnages were reported as inferred 
rather than demonstrated, or because the demonstrated 
resources were very small, with less than 50,000 t of con- 
tained primary lead or zinc metal. These 37 mines and 
deposits contained approximately 200,000 t of primary lead 
and 1.7 million t of primary zinc. 

Mines and deposits that have resources containing both 
lead and zinc were classified under the primary commodity 
that generated the larger percent of revenues at January 1982 
prices. Thus, mines often considered primary lead producers, 
such as the Black Cloud mine near Leadville, CO, may have 
generated higher zinc revenues than lead revenues and can 
be found classified as primary zinc mines in this evaluation. 
In some cases, the revenues generated by another 
commodity, such as gold, silver, or copper, were larger than 
those revenues generated by the lead or zinc, but the opera- 
tion was classified according to which of the two studied com- 
modities, lead or zinc, generated the greater amount of 
revenues. Figure 1 shows the locations of the mines and 
deposits classified as primary lead operations, while figure 
2 shows the primary zinc operations. 



evaluated as primary lead operations for this study total 315.3 
million t with a weighted average in situ grade of 6.46 pet. 
These in situ resources contain 20.4 million t of primary lead 
and approximately 3.8 million t of byproduct zinc. Table 4 is 
a listing, by property, of the resource tonnages and in situ 
grades for the primary lead operations. 

In addition to the 20.4 million t of primary lead, 6.9 million 
t of lead is contained in mines and deposits that have been 
classified as primary zinc operations. This results in a U.S. 
total of 27.3 million t of contained lead from all operations 
recovering lead for this evaluation. 

As ilfustrated in table 5, approximately 89 pet (18.1 
million t) of the lead contained in demonstrated resources 
is potentially available from the nine producing primary lead 
operations. The remaining five mines and deposits contain 
2.3 million t of lead. Total potentially recoverable 5 lead from 
the 14 primary operations is 17.5 million t of lead with 2.4 
million t of byproduct zinc. In addition to primary lead 
resources, 5.6 million t of lead is potentially recoverable as 
a byproduct from the primary zinc resources. 



DOMESTIC LEAD CAPACITY 

After the lead concentrate leaves ,the mill, it first goes 
to a smelter and then to a refinery. There are currently five 
operating primary lead smelters in the United States, and 
three of these facilities also include refineries. The other two 
lead smelter facilities handle concentrates on a custom basis 
and then ship the concentrates to a fourth refinery at Omaha, 
NE. The locations and capacities of U.S. and Canadian 
smelters and refineries utilized for this evaluation are shown 
on figure 3. 



PRIMARY LEAD RESOURCES 

Demonstrated resources for the 14 mines and deposits 



5 Recoverable is used to describe the amount of lead or zinc contained in 
the final product. It was assumed that all lead would be processed to lead 
bullion, and zinc would be processed to zinc slab. 




FIGURE 1.— Locations of primary lead mlnea and deposits. 



KERR AMERICAN- 
BLUE HILL 




FIGURE 2.— Locations of primary zinc mines and deposits. 
Table 4. — Demonstrated resources for primary lead mines and deposits 



State and property 



Production 



Status 



Years 1 



Resources, 1 3 t 



Lead 



Zinc 



Grade, pet Contained, 10 3 t Grade, pet Contained, 10 3 t 



Colorado: Bulldog 

Idaho: Luck Friday 

Missouri: 

Boss-Bixby 

Brushy Creek Division 

Buick Mine 

Fletcher 

Higdon-Bonne Terre 

Indian Creek 

Magmont Mine 

Milliken Mine 

Viburnum No. 28 and No. 29 . 

Viburnum No. 35 

West Fork 

Utah: Ontario 



W 
W 

W 
44 
25 
38 
14 

5 
38 
21 
34 
W 
32 

7 



w 
W 

W 

48,121 

45,336 

40,722 

2,551 

2,717 

34,703 

41,162 

56,900 

W 

13,605 

1,554 



W 
W 

W 
5.97 
7.00 
8.67 
8.05 
2.55 
6.33 
5.75 
5.81 

W 
7.31 
8.52 



W 
W 

W 

2,873 

3,174 

3,531 

205 

69 

2,197 

2,367 

3,306 

W 

995 

132 



W 
W 

W 
1.14 
1.90 

.61 
2.20 

NA 
1.15 
2.30 

.47 
W 

.87 
5.45 



w 
W 

W 
549 
861 
248 

56 

NA 
399 
947 
267 

W 
118 

85 



Total or weighted average 



NAp 



NAp 



315,262 



6.46 



20,363 



1.20 



3,752 



N 
W 



Nonproducing property as ol January 1 , 1 982. 
Withheld, company proprietary data. 



NA Not available. NAp Not applicable. P Producing property as of January 1, 1982. 

' Estimated number of production years remaining as of January 1 , 1 982. 



Table 5. — Summary of demonstrated resources values for domestic lead 



Status 



Number of properties 



Resources 



10 3 t 



pet 



Grade, 1 pet 



Contained lead 



10 3 t 



pet 



Recoverable lead 



10 3 t 



pet 



Primary lead: 

Producer 

Nonproducer 

Total 

Byproduct lead: 

Producer 

Nonproducer 

Total 

Grand total 35 

NAp Not applicable. ' Weighted average 



9 
5 


274,967 
40,295 


87 
13 


6.58 
5.65 


18,086 
2,277 


89 
11 


15,592 
1,928 


89 

11 


14 


315,262 


100 


6.46 


20,363 


100 


17,520 


100 


5 
16 


1 1 ,439 
379,860 


3 
97 


1.74 
1.76 


199 

6,692 


3 
97 


139 
5,439 


3 
97 


21 


391,299 


100 


1.76 


6,891 


100 


5,578 


100 



706,561 



NAp 



3.86 



27,254 



NAp 



23,098 



NAp 






TRAIL. BRITISH COLUMBIA 

,272,000 t/yr(Zn) 

[j80,000 t/yr(Pb) 




LEGEND 
▲ Lead smelterand/or refinery 
■ Zinc refinery 

FIGURE 3.— Locations of smelter and refinery facilities utilized. 



Mine production levels from 1977 to 1981 averaged 
51 8, (XX) t of primary lead per year (2). The majority of the 
primary lead resources included in this evaluation are 
available from currently producing operations, with adequate 
resources to maintain fairly constant production levels (be- 
tween 500,000 and 600,000 t of primary lead per year) over 
the next 20 yr. 

The 1 982 refinery capacity was 595,000 1 of lead bullion 
per year from four refineries, not including the Bunker Hill 
facility. Lead refinery capacity is adequate to cover present 
production needs; however, the annual probable U.S. de- 
mand for primary lead in the year 2000 has been forecasted 
at 800,000 t/yr (78). Assuming that the domestic refining 
capacity is maintained and not replaced by imported refined 
products, the annual domestic primary lead refinery capac- 
ity would need to be increased by approximately 205,000 t 
in order to attain the projected annual domestic refinery 
capacity of 800,000 t of primary refined lead by the year 2000. 

The peak annual production level for the primary lead 
operations evaluated would only be 581,000 t of primary 
refined lead per year, and the current smelter-refinery capac- 
ity of 595,000 t would be sufficient. Although the smelter- 
refinery capacity would need to be increased by the year 2000 
to meet the projected volume of 800,000 1 of primary refined 
lead per year, tne resources included in this evaluation could 
adequately meet the demand if domestic annual production 
levels were increased. The peak rate for this evaluation, 
581 ,000 t, was arrived at by assuming that current domestic 
production levels remain constant and that all preproduction 
development work began January 1, 1982. The cumulative 
demand through the year 2000 is forecast at 13.3 million t 
of recovered lead (18). The 14 operations included in this 
evaluation could provide approximately 17.5 million t of 
recoverable lead over their collective production lives; 
however, not all of this tonnage is contained in currently 
economical resources. 



PRIMARY ZINC RESOURCES 

Demonstrated resources for the 53 mines and deposits 
evaluated as primary zinc operations for this study total 1 .04 
billion t with a weighted average in situ grade of 4.73 pet zinc. 
These in situ resources contain 49.2 million t of zinc and ap- 
proximately 6.9 million t of byproduct lead. See table 6 for 
a property listing of the resource tonnages and in situ grades 
for the primary zinc operations. 

The 53 primary zinc mines and deposits evaluated for 
this study contain 49.2 million t of zinc, and an additional 3.8 
million t of zinc is contained as a byproduct in mines and 
deposits that have been classified as primary lead operations. 
This results in a U.S. total of nearly 53 million t of contained 
zinc from 65 of the 67 mines and deposits evaluated. Only 
two of the deposits evaluated for this study did not recover 
zinc. 

As illustrated in table 7, only 15 pet (162.6 million t) of 
the in situ primary zinc resources containing 6.2 million t of 
zinc are available from the 16 currently producing mines. 
From these current producers, 4.2 million t of primary zinc 
and 139,000 t of byproduct lead could be recovered. 

As of January 1 , 1982, 37 of the 53 primary zinc opera- 
tions included in this evaluation were either on standby status, 
closed indefinitely, or were in various stages of development. 
Of the 877 million t of demonstrated primary zinc resources 
potentially available from these 37 operations, 146 million t 
is potentially available from two large deposits, the Red Dog 
in Alaska and the Crandon deposit in Wisconsin. 

The Red Dog deposit is currently the largest primary zinc 
deposit in the United States with reported demonstrated 
resources of 77.1 million t and an in situ zinc grade of 17.1 
pet (19). The high zinc grades for these two deposits increase 
the weighted average grade for all primary zinc mines and 
deposits included in this study by 1 .14 pet, from 3.59 to 4.73 
pet. As illustrated in table 8 the Red dog deposit alone has 



Table 6.— Demonstrated resources for primary zinc mines and deposits 



Production 

State and property — , Resources, 10 3 1 

Alaska: 

Arctic N 10 30,838 

Greens Creek N 16 3,810 

Lik N W W 

Red Dog. N 71 77,095 

Colorado: 

Black Cloud (Leadville Unit) P 6 1 ,337 

Idarado N 9 3,754 

Sunnyside P 6 1 ,542 

Idaho: 

Bunker Hill N W W 

Star-Morning P W W 

Illinois: Minerva No. 1-Spivey P W W 

Kentucky: 

Burkesville Project N W W 

Fountain Run N W W 

Maine: 

Bald Mountain N 19 32,659 

Kerramerican-Blue Hill N W W 

Montana: Butte District Zinc N W W 

Nevada: 

Ruby Hill N W W 

Ward Mountain N W W 

New Jersey: Sterling P 8 1 ,362 

New Mexico: Pinos Altos N 10 7,000 

New York: 

Balmat P 6 6,218 

Pierrepont P 2 17 2,358 

Pennsylvania: Friedensville Mine P W W 

Tennessee: 

Beaver Creek P 7 3,805 

Big War Creek N 8 2,136 

Carthage Property N W W 

Copperhill P 40 39,656 

Coy N 15 3,550 

Cub Creek N W W 

Cumberland N W W 

Cumberland Deposit N W W 

Cumberland Property N W W 

East Gainesboro N W W 

Gainesboro N W W 

Gordonsville-Elmwood P 16 26,984 

Hartsville N W W 

Hartsville Area N W W 

Idol...: P 8 2,073 

Immel N 55 31 ,700 

Jefferson City Mine P 19 926 

Lost Creek P 15 1,849 

New Market P . 71 50,651 

Pall Mall N W W 

Right Fork N W W 

Roaring River N W W 

Stonewall N 18 6,930 

Young N 32 27,100 

Zinc Mine P W W 

Washington: 

Boundary Dam-Metaline Falls N W W 

Washington Zinc Unit N W W 

Wisconsin: 

Crandon N 23 65,800 

Crawhall-Elmo No. 3 N 5 1,276 

Pelican River N 4 1 ,450 

Shullsburg-Bearhole N 5 2,441 

Total or weighted average NAp NAp 1 ,039,630 4.73 

N Nonproducing property as of January 1, 1982. NA Not available. NAp Not applicable. 
P Producing property as of January 1 , 1982. W Withheld, company proprietary data. 
' Estimated number of production years remaining as of January 1, 1982. 
2 Began production April 1 982. 



Zinc 



Lead 



Grade, pet 


Contained, iCt 


Grade, pet 


Contained, 10 3 1 


5.50 


1,696 


1.00 


308 


10.04 


383 


3.29 


125 


W 


W 


W 


W 


17.10 


13,183 


5.00 


3,855 


10.08 


135 


4.97 


66 


3.89 


146 


2.72 


102 


3.40 


52 


2.10 


32 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


2.00 


653 


1.50 


490 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


18.90 


257 


NA 


NA 


3.00 


210 


NA 


NA 


8.50 


529 


.45 


28 


20.13 


475 


NA 


NA 


W 


W 


W 


W 


3.90 


148 


NA 


NA 


4.40 


94 


NA 


NA 


W 


W 


W 


W 


1.26 


502 


NA 


NA 


3.96 


141 


NA 


NA 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


4.60 


1,241 


NA 


NA 


W 


W 


W 


W 


W 


W 


W 


W 


4.40 


91 


NA 


NA 


3.08 


976 


NA 


NA 


4.30 


40 


NA 


NA 


3.60 


67 


NA 


NA 


2.80 


1,418 


NA 


NA 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


4.37 


303 


NA 


NA 


3.25 


881 


NA 


NA 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


W 


5.80 


3,816 


.50 


329 


3.70 


47 


.10 


1 


8.00 


116 


NA 


NA 


3.00 


73 


.15 


4 



49,197 



1.76 



6,891 



27 pet of the total contained primary zinc. It also makes a 
major contribution to the amount of byproducts recoverable 
with 65 pet of the total byproduct lead and 42 pet of the total 
byproduct silver potentially recoverable from all primary zinc 
operations evaluated for this study. 



Although the Crandon deposit has 65.8 million t of 
resources and a higher than average zinc grade, 5.8 pet ver- 
sus 4.73 pet for the United States, it does not contribute the 
large amounts of primary zinc and byproduct lead that the 
Red Dog deposit does. The Crandon deposit could poten- 



Table 7. — Summary of demonstrated resources values for domestic zinc 



». . Number of 

Status 

properties 

Primary zinc: 

Producer 

Nonproducer 

Total 

Byproduct zinc: 

Producer 

Nonproducer 

Total 

Grand total 65 

NAp Not applicable ' Weighted average 



Resources 
10 3 1 pet 



Grade.' pet 



Contained zinc 
10 3 t pet 



Recoverable zinc 
10 3 t pet 



16 
37 


162.622 
877.008 


16 
84 


380 
4.91 


6,178 
43,019 


13 
87 


4,151 
35,730 


10 
90 


53 


1 .039.630 


100 


4.73 


49.197 


100 


39,881 


100 


7 
5 


271.515 
40,295 


87 
13 


1.23 
1.05 


3.330 
422 


93 

7 


2,130 
246 


90 
10 


12 


311.810 


100 


1.20 


3,752 


100 


2.376 


100 



1.351.440 



NAp 



3.92 



52,949 



NAp 



42,257 



NAp 



Table 8. — Comparison of Crandon and Red Dog deposits' 
resource values with total primary zinc resource values 









Operations' 




Total 




Crandon 


Red Dog 


Others 


resources 


Demonstrated resources: 










Tonnage 


10 3 t. . 


65.800 


77.095 


896.735 


1.039,630 


Percent of total 




6 


7 


86 


100 


In situ zinc grade 


. pet. . 


58 


17 1 


2 3.59 


2 4.73 


Contained zinc 












Tonnage 


10 3 1. . 


3.816 


13.183 


32.198 


49.197 


Percent of total 




8 


27 


65 


100 


Recoverable zinc 












Tonnage . . 


. 10 3 1 . 


3.108 


1 1 .628 


25,146 


39.881 


Percent of total 




8 


29 


63 


100 



' Total of 53 2 Weighted average in situ grade zinc. 

NOTE — Data may not add to totals shown because of independent rounding. 



tially recover 8 pet (3.1 million t) of the total recoverable zinc 
ana 4 pet of the byproduct lead evaluated for this study. Like 
the Red Dog deposit, Crandon also makes a major contribu- 
tion to the total amount of byproducts recoverable from all 
of the primary zinc operations evaluated, with 10 pet of the 
total byproduct silver, 29 pet of the total byproduct copper, 
and 47 pet of the total byproduct gold. 

In summary, a total of 4.2 million t of recoverable primary 
zinc is potentially available from the 16 producing operations, 
and a total of 35.7 million t of recoverable zinc is potentially 
available from the 37 operations not currently in production. 
An additional 5.4 million t of byproduct lead could also be 
recovered from the nonproducing operations, which is 97 pet 
of the total potentially recoverable byproduct lead. Including 
the 2.4 million t of byproduct zinc available from the primary 
lead resources, total zinc potentially recoverable from the 
mine and deposits evaluated for this study was estimated at 
42.3 million t. 



DOMESTIC ZINC CAPACITY 

Zinc concentrates are processed domestically by elec- 
trothermic and roast-leach-electrolytic methods that produce 
slab (primary refined) zinc, and as of January 1 , 1982, there 
were five primary slab zinc processing facilities operating in 
the United States. With a slight increase in capacity at the 
Monaca. PA, facility, the 1982 postmill processing capacity 
was 390,000 t of refined zinc per year, down from 484,000 
t of capacity in 1981, with the closure of Bunker Hill. This 
low capacity level would be insufficient if a large number of 
the currently inactive mines or undeveloped deposits were 
to come on line together in the future. Increased production 
levels, and even additional postmill processing capacity, 
would be required to meet increased concentrate production 
rates. The maximum annual smelter production level 



established for the operations included in this evaluation was 
approximately 1.1 million t of slab zinc per year. However, 
this production level was arrived at by assuming that current 
production levels for the 16 producing operations would re- 
main constant, and that all preproduction development work 
for the 37 nonproducing mines and deposits began January 
1, 1982. 

Total probable demand for slab (primary refined) zinc for 
the year 2000 has been forecast at 1..05 million t (20). An- 
nual domestic mine production requirements have been pro- 
jected at 640,500 t of zinc recovered. Because the current 
domestic primary smelter capacity of 390,000 t (excluding 
Bunker Hill) would be inadequate to process this increased 
production level, additional postmill processing capacity 
would be required. If the United States was to process a 
greater percentage of its own resources and decrease its 
dependency on foreign sources of zinc in the future, the 
domestic mine production levels required would exceed the 
projected 640,500 1 of slab zinc per year. However, there is 
a chance that continued low utilization levels may result in 
the closure of some additional facilities, thereby further 
decreasing the current domestic postmill processing capacity 
rather than increasing it. 

Total cumulative recoverable zinc through the year 2000 
has been forecast at 23 million t (20). Potentially, 39.9 million 
t of zinc could be recovered from the 53 primary zinc opera- 
tions over their collective production lives. It should be 
stressed that 90 pet of the potentially recoverable zinc would 
come from undeveloped deposits or mines that are not cur- 
rently producing owing to high operating costs and depressed 
metal prices. 



SUMMARY OF DOMESTIC RESOURCES 

In summary, without regard to economics, the lead and 
zinc resources available from the 67 mines and deposits 
included in this evaluation could provide adequate sources 
of metal over the next 20 yr, but postmill processing capacities 
would need to be increased in order to maintain the current 
level of self-sufficiency for lead, or possibly decrease the U.S. 
dependence on foreign sources of zinc. Greater utilization 
of foreign facilities in Canada, Japan, and Europe could 
lessen the burden of building additional facilities to process 
excess domestic mine production, however, utilization of the 
foreign facilities would not be of much help towards a goal 
of postmill processing self-sufficiency. 

An option available to several of the larger zinc opera- 
tions, such as the Crandon in Wisconsin, or several of the 
larger Tennessee operations, could be to build their own 
postmill processing facilities. Although the economic feasibil- 
ity of additional facilities was not evaluated, new facilities 
would help to insure adequate processing capabilities, reduce 
transportation distances and associated costs, and above all, 
would reduce the dependency on foreign sources for zinc. 



10 



GENERAL GEOLOGY 



Lead and zinc occur together largely because of 
similarities in their chemical behavior (21). This relationship 
is well illustrated in the sites evaluated. Five of the mines 
evaluated appear in the list of the top 15 producers for both 
lead and zinc (1-2). Twelve of the fourteen properties 
evaluated as primary lead properties for this study also con- 
tain recoverable zinc, and 20 of the 53 mines and deposits 
evaluated as primary zinc operations also contain recoverable 
lead. In addition, other minerals, particularly silver, copper, 
and gold, frequently occur with the lead and zinc minerals. 
The reader may refer to appendix C for a very general discus- 
sion on the geology of the deposits evaluated, which are listed 
on a State-by-State basis. 

Most exploitable lead and zinc ores can be divided into 
five principal categories based on differences in their geologic 
occurrences: (a) volcanic-hosted submarine exhalative 
massive sulfide deposits, (b) sediment-hosted submarine ex- 
halative deposits, (c) strata-bound carbonate-hosted deposits, 
(d) strata-bound sandstone-hosted deposits, and (e) vein, 
replacement, and contact metasomatic deposits (22). Of the 
67 sites evaluated, 43 occur in Mississippi Valley-type (MVT) 
deposits, which are members of the strata-bound carbonate- 
hosted category (22). The other 24 mines and deposits oc- 
cur in all of the remaining deposit types and will be referred 
to as non-Mississippi Valley-type (NMVT) deposits. Table 9 
is a list of those deposits classified as NMVT deposits. 

MVT deposits generally occur in marine carbonate rocks 
deposited in shallow water on stable craton areas, and 
mineralization is generally restricted to particular horizons 
within certain formations. The deposits are generally more 
extensive laterally than vertically, and open-space fillings are 
predominant. 

The majority of all domestic lead and zinc resources are 
contained in MVT deposits, and 9 of the top 15 producers 
of both lead and zinc occur in MVT deposits. The 43 MVT 
deposits account for approximately 98 pet of the total in situ 
primary lead resources and 67 pet of the total in situ primary 
zinc resources. 

The percentages are even higher for the producing mines 
evaluated. Approximately 98 pet of the primary lead resources 
and approximately 81 pet of the primary zinc resources in 
producing mines are located in MVT deposits. Resources 
from undeveloped MVT deposits or nonproducing mines ac- 
count for approximately 99 pet of the remaining primary lead 
resources and 64 pet of the remaining primary zinc resources 
(1 pet and 26 pet are nonproducing NMVT deposits for lead 
and zinc, respectively). While the ratio of MVT to NMVT 
deposit types will probably remain consistent for the future 
production of lead, a higher percentage of zinc could become 
available from NMVT deposits. Consequently, NMVT deposits 



Table 9.— Non-Mississippi Valley-type deposits 

Primary 
State and property commodity 

Alaska: 

Lik Zinc. 

Arctic Do. 

Greens Creek Do. 

Red Dog Do. 

Colorado: 

Black Cloud Do. 

Bulldog Lead. 

Idarado Zinc. 

Sunnyside Do. 

Idaho: 

Bunker Hill Do. 

Lucky Friday Lead. 

Star-Morning Zinc. 

Maine: 

Bald Mountain Do. 

Kerramerican-Blue Hill Do. 

Montana: Butte District Zinc Do. 

Nevada: 

Ruby Hill Do. 

Ward Mountain Do. 

New Jersey: Sterling Do. 

New Mexico: Pinos Altos Do. 

New York: 

Balmat Do. 

Pierrepont Do. 

Tennessee: Copperhill Do. 

Utah: Ontario Lead. 

Wisconsin: 

Crandon Zinc. 

Pelican River Do. 



will probably be the source of a higher percentage of zinc 
production in the future. 

The NMVT deposits evaluated contain a higher value of 
recoverable byproducts than do the MVT deposits. Higher 
byproduct revenues generated from NMVT deposits will off- 
set a portion of the production costs and could make the 
NMVT deposits more attractive for development. This sub- 
ject is dealt with more completely in the following section on 
deposit type and the relationship to byproduct content. 

A difference in mining methods and costs also exists be- 
tween MVT and NMVT deposits. The majority of the MVT 
deposits are mined using some form of room-and-pillar min- 
ing, with operating costs that are generally lower than those 
methods used to mine the NMVT deposits. This subject is 
dealt with more thoroughly in the "Mining Methods and 
Costs" section. 



DEPOSIT TYPE AND RELATIONSHIP TO BYPRODUCT CONTENT 



Some of the factors that determine the type of mineralogy 
occurring in any deposit are temperature, pressure, and depth 
of mineral deposition; chemistry of the host rock; and 
chemistry of the ore-bearing fluids. These and other factors 
contribute to the uniqueness of any deposit and determine 
the type of mineral assemblage that results. Differences in 
mineral assemblage strongly influence the economics of the 
lead and zinc operations evaluated. This is reflected in the 
fact that production of byproduct gold, silver, and copper 
varies widely between MvT and NMVT deposits. 

Tables 10 and 11 show what commodities were 
recovered as byproducts, in addition to the primary com- 
modity, during the evaluation of each site. In a few instances, 
mines in this study may recover other byproducts in addition 



to those listed. If data about additional byproducts were in- 
sufficient, recovery sporadic, or the mine did not receive pay- 
ment for that byproduct from the smelter, then the commodity 
was not included in the evaluation. Therefore, while the trends 
discussed in this evaluation are representative of the domestic 
operations included, it should be kept in mind that they are 
not absolute. 

Revenues generated by byproduct gold, silver, and cop- 
per may be substantial, and in some cases may be the deter- 
mining factor as to whether a particular deposit is exploited, 
or whether a particular mine remains open. However, not all 
deposits, regardless of MVT or NMVT classification, contain 
gold, silver, or copper. Of those that do contain these 
byproducts, significant differences exist. 



11 



Table 10. — Commodities recovered as byproducts at primary 
lead properties 



Table 1 1 . — Commodities recovered as byproducts at primary 
zinc properties 



State and property 



Deposit 
type 



Commodities 



Colorado: Bulldog NMVT 

Idaho: Lucky Friday NMVT 

Missouri: 

Boss-Bixby MVT 

Brushy Creek Division MVT 

Buck MVT 

Fletcher MVT 

Hkjdon-Bonne Terre MVT 

Indian Creek MVT 

Magmont MVT 

Milliken MVT 

Virbumum No 28 and No. 29 . MVT 

Virburnum No 35 MVT 

West Fork MVT 

Utah: Ontario NMVT 

MVT Mississippi Valley type NMVT 



Silver. 

Zinc, silver, gold 

Zinc, copper 

Zinc, copper, silver, cadmium. 

Do. 

Do 
Zinc, copper. 
Copper, silver 

Zinc, copper, silver, cadmium. 
Zinc, silver, cadmium. 
Zinc, copper, silver, cadmium. 
Zinc, copper 

Zinc, copper, silver, cadmium. 
Zinc, silver 



Non-Mississippi Valley type 



Gold is not presently recovered from operations located 
in MVT deposits; gold is credited for 1.2 to 77.5 pet 6 of the 
revenues at NMVT operations where it is recovered. These 
percentages of revenues are based on the January 1982 
prices of S384.12 per troy ounce of gold, $0.30 per pound 
of lead, and $0.42 per pound of zinc. 

Most of the MVT deposits included in this study do not 
contain recoverable amounts of silver. Silver is recovered only 
from eight of the MVT deposits located in the Southeast 
Missouri District. However, owing to their size, these eight 
operations are responsible for 19 pet of the total silver 
recovered from all lead and zinc operations included in the 
evaluation. Using prices of $8.03 per troy ounce of silver, and 
$0.30 per pound of lead, silver is credited for only 0.1 to 4.5 
pet of the revenues generated at the MVT deposits located 
in the Southeast Missouri District. In the NMVT deposits 
where silver is recovered, it accounts for 28.3 to 93.4 pet of 
the revenues generated at mines and deposits evaluated as 
primary lead operations, and using a price of $0.42 per pound 
of zinc, silver accounts for 0.4 to 38.2 pet of the revenues 
generated for mines and deposits evaluated as primary zinc 
operations. 

Copper is recovered from 10 of the MVT deposits. All 
of these are located in the Southeast Missouri District, and 
are anomalously enriched in copper relative to most other 
MVT deposits. The 10 Missouri operations are responsible 
for 16 pet of the total copper recovered from lead and zinc 
operations included in this evaluation. Using prices of $0.79 
per pound of copper and $0.30 per pound of lead, copper 
is credited for up to 26.2 pet of the revenues generated at 
the operations located in the Southeast Missouri District. Cop- 
per recovered from primary zinc operations located in NMVT 
deposits accounts for 6.2 to 61.9 pet of the revenues at a 
$0.42-per-pound price for zinc. 

Although table 9 shows that the deposits in the Southeast 
Missouri District are considered to be MVT deposits, they are 
atypical, and their classification as such is currently being 
reviewed. Their lead-zinc-silver-copper (and sometimes cobalt 
and nickel) ores are extremely unusual when compared with 
ores of other MVT deposits. In addition, small amounts of gold 
have also been produced from the some of the Missouri 
deposits in the past, and it is probable that at some time in 
the future significant, though small amounts, of gold will be 
recovered from copper-cobalt-nickel ore bodies not yet ex- 
ploited (21). Most MVT deposits do not contain recoverable 



•Operations receiving a large percentage of their revenues from commodities 
that were considered byproducts for this evaluation may actually be recovering 
the lead and/or zinc as coproducts These operations are included herein as 
primary lead or zinc operations because they recover significant quantities of 
lead and/or zinc. 



State and property Deposit Commodities 
type 

Alaska: 

Arctic NMVT Lead, copper, silver. 

Greens Creek NMVT Lead, silver, gold. 

Lik NMVT Lead, silver. 

Red Dog NMVT Do. 

Colo r ado: 

Black Cloud NMVT Lead, silver, gold. 

Idarado NMVT Lead, copper, silver, gold. 

Sunnyside NMVT Do. 

Idaho: 

Bunker Hill NMVT Lead, silver. 

Star-Morning NMVT Do. 

Illinois: Minerva No. 1-Spivey MVT Lead, fluorspar, barite. 

Kentucky: Burkesvllle Project MVT Lead. 

Maine: 

Bald Mountain NMVT Copper. 

Kerramencan-Blue Hill NMVT Do. 

Montana: Butte District Zone NMVT Lead, copper, silver. 

Nevada: 

Ruby Hill NMVT Lead, silver, gold. 

Ward Mountain NMVT Lead, copper, silver. 

New Mexico: Pinos Altos NMVT Copper. 

New York: Balmat NMVT Lead, silver. 

Pennsylvania: Friedensville Mine . . . MVT Limestone. 
Tennessee: > 

Copperhiil NMVT Copper, iron. 

Cumberland Deposit MVT Cadmium. 

Cumberland Property MVT Do 

Gordonsville-Elmwood MVT Limestone. 

Jefferson City Mine MVT Do. 

Right Fork MVT Cadmium. 

Washington: 

Boundary Dam-Metaline Falls ... . MVT Lead. 

Washington Zinc Unit MVT Do. 

Wisconsin: 

Crandon NMVT Lead, copper, silver, gold 

Crawhall-Elmo No 3 MVT Lead 

Pelican River NMVT Copper. 

Shullsburg-Bearhole MVT Lead. 

MVT Mississippi Valley type. NMVT Non-Mississippi Valley type. 



amounts of silver, copper, nickel, cobalt, or gold. If the 
southeast Missouri deposits were to be reclassified as NMVT 
deposits at some point in the future, there would be no silver, 
copper, or gold recovered from any of the domestic MVT 
deposits evaluated. This would make the previous points on 
deposit type and byproduct content even stronger. 

In summary, the NMVT deposits evaluated generally con- 
tain a higher value of recoverable byproducts than do the MVT 
deposits. Revenues generated from byproducts as a percen- 
tage of total revenues generated from NMVT deposits may 
range as high as 93 pet for silver, 78 pet for gold, and 62 pet 
for copper using the January 1982 market prices for these 
commodities. MVT deposits do not have the high quantity 
of byproducts that NMVT deposits do, and the percentage 
of total revenues generated from byproducts is much lower; 
only up to 4.5 pet for silver and 26 pet for copper. There is 
no gold presently recovered from MVT deposits. The high 
byproduct revenues generated from NMVT deposits can off- 
set a portion of the production costs and make the NMVT 
deposits more attractive to development. Therefore, NMVT 
deposits are likely to be the source of a higher percentage 
of zinc production in the future. 

The effects of fluctuating metal prices on the economic 
availability of lead and zinc resources potentially recoverable 
from the mines and deposits evaluated are discussed later 
in the "Sensitivity Analyses" section. The difference in min- 
ing methods and costs that exists between MVT and NMVT 
deposits is discussed in the following section. 



12 



MINING METHODS AND COSTS 



There is a definite correlation between the geology of 
a particular deposit and the type of mining method used. All 
of the MVT deposits evaluated are geologically similar and 
the methods used to mine them are also similar. Figure 4 illus- 
trates this relationship between the deposit type and the min- 
ing method. Ninety-eight percent of the resource tonnages 
classified as MVT deposits are mined by room-and-pillar, or 
room-and-pillar in combination with some other mining 
method. Conversely, only 4 pet of the resource tonnages 
classified as NMVT deposits are mined solely by room-and- 
pillar methods. 

Tables 12 and 13 show the mining methods used or pro- 
posed in the lead and zinc sites evaluated. All primary lead 
operations, and all but five of the primary zinc operations 
evaluated, either utilize or plan to utilize underground min- 
ing methods. The remaining five sites, all NMVT primary zinc 
deposits, used or planned to use open pit methods. Most of 
the deposits are mined by room-and-pillar, sublevel stoping, 
shrinkage stoping, or cut-and-fill methods. Room-and-pillar 
mining was utilized most frequently, either alone or in com- 
bination with sublevel stoping or shrinkage stoping methods. 
The latter methods are used in portions of an ore body that 
are not amenable to room-and-pillar mining owing to its 
shape, attitude, or structural features. Historically, sublevel 
stoping and shrinkage stoping have both been used in com- 
bination with room-and-pillar methods in the Tennessee- 
Kentucky mines where breakthrough ore bodies were en- 
countered during the course of mining. 

Drilling at all of the underground operations is usually 
done by jumbo drills, but jackleg drills and vertical long-hole 
air-track drills are sometimes used when conditions warrant 
them. Where distances are short, hauling is usually done by 
load-haul-dumpers (LHD's), but longer hauls may be done 
with trucks, converyors, or rail equipment. Many of the mines 
have underground crushers that crush the ore before it is 
hoisted. Most of the mines are accessed by shafts, but in- 
clines and, to a lesser extent, adits may also be used. 



Table 12. — Mining methods used or proposed for primary lead 
operations 

State and property Mining methods 

Colorado: Bulldog Undercut and fill. 

Idaho: Lucky Friday Cut and fill. 

Missouri: 

Boss-Bixby Room-and-pillar. 

Brushy Creek Division Do. 

Buick Do. 

Fletcher Do. 

Higdon-Bonne Terre Do. 

Indian Creek Do. 

Magmont Do. 

Milliken Mine Do. 

Virburnum No. 28 and No. 29 Do. 

Virburnum No. 35 Do. 

West Fork Do 

Utah: Ontario Cut and fill. 



ROOM-AND-PILLAR METHODS 

Room-and-pillar mining is used where ore bodies are 
comparatively flat lying or where the ore occurs in large 
bodies. In room-and-pillar mining, chambers are excavated 
and pillars are left standing to provide support for the over- 
lying rock. The pillars may be recovered during the last stages 
of mining, if they are of sufficient grade to make recovery 
economical. 

Approximately 98 pet of the primary lead resource ton- 
nage and 8 pet of the primary zinc resource tonnage are 
mined by room-and-pillar methods only. Figure 5 shows a 



Table 13. — Mining methods used or proposed for primary zinc 
operations 

State and property Mining methods 

Alaska: 

Arctic Open pit. 

Greens Creek Underhand cut and fill. 

Lik Open pit. 

Red Dog Do. 

Colorado: 

Black Cioud Room-and-pillar with fill. 

Idaiado Shrinkage stoping. 

Sunnyside Do. 

Idaho: 

Bunker Hill Room-and-pillar, cut and fill. 

Star-Morning Cut and fill. 

Illinois: Minerva No. 1-Spivey 1 Room-and-pillar, shrinkage stoping. 

Kentucky: 

Burkesville Project Do. 

Fountain Run Do. 

Maine: 

Bald Mountain Open pit. 

Kerramerican-Blue Hill Room and pillar. 

Montana: Butte District Zinc Cut and fill, sublevel cave, block caving 

with minor underhand stoping. 
Nevada: 

Ruby Hill Cut and fill, open stope. 

Ward Mountain Room-and-pillar. 

New Jersey: Sterling Cut and fill, limited square set. 

New Mexico: Pinos Altos Open stope. 

New York: 

Balmat Room-and-pillar, sublevel stoping, 

contour mining, sublevel benching, 
uphill slab and lifter stoping. 

Pierrepont Do. 

Pennsylvania: Friedensville Mine. . Room-and-pillar, open stope. 
Tennessee: 

Beaver Creek Room-and-pillar. 

Big War Creek Do. 

Carthage Property Room-and-pillar, sublevel stoping. 

Copperhill Sublevel stoping, pillar, open pit. 

Coy Room-and-pillar, shrinkage stoping. 

Cub Creek Room-and-pillar, sublevel stoping. 

Cumberland Do. 

Cumberland Deposit Do. 

Cumberland Property Do. 

East Gainesboro Do. 

Gainesboro Do. 

Gordonsville-Elmwood Do. 

Hartsville Do. 

Hartsville Area Do. 

Idc! Room-and-pillar. 

Immel Room-and-pillar, shrinkage stoping. 

Jefferson City Mine Do. 

Lost Creek Do. 

New Market Do. 

Pall Mall Room-and-pillar, sublevel stoping. 

Stonewall Do. 

Right Fork Do. 

Roaring River Do. 

Young Room-and-pillar, shrinkage stoping. 

Zinc Mine Room-and-pillar. 

Washington: 

Boundary Dam-Metaline Falls . . Room-and-pillar. 

Washington Zinc Unit Blasthole stoping. 

Wisconsin: 

Crandon Sublevel blasthole, open stope with fill. 

Crawhall-Elmo No. 3 Room-and-pillar. 

Pelican River Cut and fill. 

Shullsburg-Bearhole. Room-and-pillar. 

1 Minerva No. 1 is mined by room-and-pillar and Spivey is mined by shrinkage 
stoping. They were combined for evaluation purposes because they use a 
common mill. 

breakdown of mining methods by primary commodity. Nine- 
teen of the twenty-one mines that use room-and-pillar 
methods solely are MVT deposits. All of the mines and 
deposits in the Southeast Missouri District and the Copper 



13 



Mississippi VcHky-type deposits 

All other methods 
2pct 



Non-Mississippi Valley -type deposits 




All other methods 
II pet 



Room-and-pillar only 
4 pet 



Room-and-pillar with 

shnnkoge stoping 

I2pct 




FIGURE 4.— Relationship between mining methods and deposit classification. 



Primary lead 



Any method with till 
2 pet 




Primary zinc 

Al I other methods, -Room-and-pillar only 

6 pet \ / 8 pet 




oom-and -pillar with 
shrinkage stoping 
II pet 



FIGURE 5.— Breakdown of mining methods by primary commodity. 



Ridge District in Tennessee were evaluated using room-and- 
pillar mining only. Mine operating costs for room-and-pillar 
mining range from $8 to $26 per metric ton, with costs at most 
of the mines in the lower third of this range. 

Table 14 provides a breakdown of mine operat'ng costs 



by mining method, MVT deposit status, and primary com- 
modity. The mine operating costs are shown as ranges to 
protect confidential company data. These ranges are quite 
wide, which illustrates the high degree of variability between 
individual operations. 



Table 14. — Selected mine operating costs' 



Mining method 


Deposit 


Cost per 


Primary 




type 


metric ton 


commodity 


------ . - - 


MVT. 


S8-S26 


Lead, zinc 


onry 


NMVT 






a :<c--3---- ■ a - Bub e.e 


M r 


8- 11 


Zinc 


Stoping 








Room-and-pillar with shrinkage 


MVT 


11- 20 


Do 


stoping 








A bOCMI methods 


NMVT 


21- 76 


Lead, zmc 


Openprt 


NMVT 


3- 24 


Zinc 



MVT Mississippi Valley type NMVT Non-Mississippi Valley type 
' Costs in January 1962 doiia's 



ROOM-AND-PILLAR WITH SUBLEVEL 
STOPING METHODS 

A combination of room-and-pillar and sublevel stoping 
methods is used at the mines in the MVT deposits in the Cen- 
tral Tennessee-Kentucky region. In sublevel stoping, 
sublevels are driven above the main levels at intervals up to 
the hanging wall. The ore is blasted and drawn through ore 
passes to the main haulage levels. Mining is started on the 
uppermost sublevels first, retreating down to the main levels. 
Pillars may or may not be left. This method is only used where 
both the walls and the ore are strong. 

Central Tennessee-Kentucky sites account for all of the 
16 deposits utilizing combined room-and-pillar and sublevel 



14 



stoping. Approximately 47 pet of the primary zinc resources 
are mined by these combined methods. Mine operating costs 
at the Central Tennessee-Kentucky sites range from $8 to 
$1 1 per metric ton. 



ROOM-AND-PILLAR WITH SHRINKAGE 
STOPING METHODS 

Shrinkage stoping is used in combination with room-and- 
pillar mining in most of the MVT deposits of the Mascot- 
Jefferson City District. In shrinkage stoping, the stopes are 
developed by blasting upward through the back of the stope 
and then using the rubble as a working floor for the next cy- 
cle of blasting. The cycle continues until the hanging wall is 
reached, and at that time the stope is mucked out. Eleven 
percent of the primary zinc resources are mined using this 
room-and-pillar with shrinkage stoping combination. Mine 
operating costs range from $11 to $20 per metric ton. 



BACKFILL METHODS 

Two percent of the primary lead resources and 1 1 pet 
of the primary zinc resources are mined using backfill 
methods. Backfill methods are used where it is necessary 
to recover as much of the ore as possible and the country 



rock is not self-supporting. After the stopes are mined out, 
they are filled with sand (mill tailings) or a sand and cement 
mixture. Mining can then proceedimmediately adjacent to 
the filled stope. Sand for the backfill is supplied by the mill- 
ing operations. 

All 12 deposits that use cut and fill, undercut and fill, or 
other methods with fill are in NMVT deposits. With the ex- 
ception of the Sterling Mine, all of the mines have concen- 
trations of precious metals. The additional expense required 
to use backfill methods is offset by the greater value of the 
ore. However, in the case of the Sterling Mine, its inexpen- 
sive milling procedures offset the high cost of mining. Mine 
operating costs for mines employing backfill methods range 
from $21 to $76 per metric ton, with costs fairly well distributed 
throughout the range. 



OPEN PIT METHODS 

All of the mines that were evaluated as using open pit 
methods are primary zinc properties, and all of them occur 
in NMVT deposits. The resources from the open pit mines 
account for approximately 1 7 pet of the domestic primary zinc 
resources evaluated. Rotary drills and blasting are used, and 
the ore is excavated by means of electric shovels and front- 
end loaders, with haulage to the mill by trucks. Operating 
costs for open pit mining range from $3 to $24 per metric ton. 



MILLING METHODS AND COSTS 



All of the sites except the Sterling Mine use generally 
the same type of milling procedures whether the ore contains 
primarily lead, zinc, or is a mixed sulfide ore. However, the 
specific methods used are dependent on the characteristics 
of the ore at each operation. The ore undergoes crushing, 
grinding, classification, and sometimes heavy media separa- 
tion. The heavy media separation reduces the amount of 
waste that goes through the rest of the milling process. The 
ore is then treated by flotation to make concentrates that are 
thickened, filtered, sometimes dried, and then stored for ship- 
ment. Up to three different concentrates may be produced 
at one mill. Lead, zinc, and copper are generally produced 
as separate concentrates. A combination lead-copper pro- 
duct is bulk floated, and then the lead and copper concen- 
trates are separated by differential flotations. The tails from 
the lead-copper circuit become the feed for the zinc circuit, 
with the zinc concentrate being the final product in the flota- 
tion process. 

Precious metals may be contained in all three of the con- 
centrates, but the highest concentrations occur in the lead 
and copper concentrates. Cadmium, on the other hand, is 
generally contained in the zinc concentrates. Sometimes a 
mill will sacrifice good recovery of the zinc concentrate to ob- 
tain maximum recovery of the more valuable lead-silver con- 
centrate, as is done at the Lucky Friday Mine. High silver 
values are also present at the Bulldog Mine, where a carbon- 
in-pulp plant has been recovering silver since 1976. This plant 
is treating old tailings in addition to the slimes from the flota- 
tion plant. At the Sunnyside Mine, sponge gold is produced 
by amalgamation of a jig concentrate high in gold and lead 
values. 



In addition to lead, zinc, or copper concentrates, other 
products may be produced at some of the milling operations. 
Fluorspar and sometimes barite concentrates are produced 
after lead and zinc flotation at the Minerva No. 1-Spivey mill. 
Depending on market requirements, various grades of the 
fluorspar can be produced. An iron concentrate is also pro- 
duced at the Copperhill mill. Agricultural limestone or other 
sand products are recovered from tailings at three produc- 
ing operations. It was assumed that no limestone would be 
recovered from any sites that were evaluated as non- 
producers at the time of this study. 

Only one site evaluated during the study does not 
beneficiate the ore. Milling operations at the Sterling Mine 
in New Jersey consist of dry crushing and grinding only. No 
further concentration of crude ore is necessary because of 
its already high natural grade of 18.9 pet zinc. The ore is sent 
directly to the company smelter. 

Automation at several of the newer large Missouri opera- 
tions makes them some of the most efficient mills in the world. 
For the operations evaluated in this study, mill operating costs 
ranged from $2 to $13 per metric ton of ore, except at the 
Sterling Mine where the ore is not beneficiated. The costs 
are variable because the milling operation at each operation 
is unique and is designed specifically for its particular ore, 
even though the same general procedures are used. Some 
factors that contribute to the wide range of milling costs are 
chemical composition of the ore, hardness of the ore, final 
grinding size needed, age of the mill, efficiency of the mill, 
quantity and quality of final products desired, and size and 
location of the mill. 



POSTMILL COSTS 



Postmill costs are normally under little control of a min- 
ing company, except in the case where a mine-mill and 
smelter-refinery complex are owned by the same company. 
The costs of transportation and postmill processing both vary 
widely, and any particular mining operation will probably send 
its concentrates to the smelter that results in the most 



favorable terms to the mining company on a delivered and 
sold basis. Because detailed information pertaining to 
transportation and postmill processing was not available (or 
was confidential) for many of the operations, it was assumed 
for this study that most concentrates were shipped to the 
nearest facility, and that a common treatment schedule was 



15 



used by all of the facilities, regardless of the location, con- 
centrate requirements, or the capacity available at any par- 
ticular facility. 

Domestic capacity was augmented by shipping lead and 
zinc concentrates in the Northwestern United States to the 
Cominco facility in Trail, British Columbia, and zinc concen- 
trates from the Maine operations were shipped to the 



Valleyfield facility in Montreal, Quebec. All concentrates from 
Alaskan operations were transported by truck, barge, and/or 
rail to the nearest port and shipped to Japan for postmill pro- 
cessing. Refer to figure 3 for a map indicating the locations 
and capacities of the U.S. and Canadian postmill process- 
ing facilities utilized. 



TRANSPORTATION 



Truck, barge, and rail rates were applied using known 
rates, if available, or estimated rates, which were supplied 
by transportation companies, for the routes over which each 
concentrate would travel. The variability and uncertainty of 
transportation costs are best illustrated by the situation that 
exists in the railroad industry. Negotiated rates (rates that are 
a result of a contractual agreement between a shipper and 
the railroad) exist only on routes where lead and zinc con- 
centrates are currently being shipped. Class rates (rates that 
apply to bulk freight) are applied to those routes that do not 
currently handle lead or zinc concentrates. Class rates are 
higher than negotiated rates, but there is no rule of thumb 
relationship to predict what the negotiated rate would be from 
any class rate. The negotiated rate decided on by the mine 
and the railroad depends upon how keenly the railroad wants 
the business, what the rail costs are over that particular por- 
tion of the track, and what kind of capital expenditures are 



necessary in order to enable the railroad to carry the con- 
centrate (23). 

Occasionally, negotiated rates or the alternative methods 
of transportation were available to a more distant facility and 
were less expensive than class rates to the nearest facility. 
In" those cases, the least expensive route and rate were ap- 
plied. In Alaska, for example, concentrates derived from this 
investigation were shipped to Japan at an average cost of 
$0.05 per pound of refined product. This can be compared 
with an average cost of $0.68 per pound of refined product 
for transporting the concentrates via a proposed interior 
Alaskan rail line to Anchorage, AK, and then by barge and 
rail to Trail, British Columbia. Actual transportation costs, 
which may vary considerably from those used in this in- 
vestigation, will depend on the transportation method(s) 
chosen, what rates can be negotiated, and the location of 
the smelter of choice. 



POSTMILL PROCESSING CONTRACT TERMS 



In actual practice, smelter terms are negotiated in- 
dividually between mines and smelters. Terms vary con- 
siderably from mine to mine and smelter to smelter owing 
to a number of different factors. Each facility is constructed 
with a particular feed in mind, and not all concentrates are 
suitable feed for all facilities. The terms of any contract will 
reflect the processor's degree of interest in acquiring a par- 
ticular concentrate. Owing to the recent shortage of zinc con- 
centrates, some smelters have been competing for concen- 
trates in order to have enough plant feed to remain open, 
with the financial terms of the contract being a secondary 
issue. An increased number of less suitable concentrates 
were also being accepted, and in these cases, the terms to 
the mines may be unusually favorable. Actual smelter con- 



tracts will vary owing to numerous factors such as changes 
in metal prices, changes in labor and power rates at the 
facilities, metallurgy of the concentrates, amount of the con- 
tained metal in the concentrates, and the moisture content 
of the concentrates. 

All of the operations were evaluated using a common 
smelter schedule because detailed information on the ex- 
pected metallurgy of concentrates at all operations was not 
available, it was unknown what facilities would accept any 
particular concentrate, and because it was unknown what 
terms would be negotiated between each mine and any par- 
ticular smelter. Smelter schedules were obtained from some 
of the companies that process zinc, lead, and copper ores, 
and a generalized smelter schedule, as shown in table 15, 



Table 15.— Smelter schedule developed for domestic lead and zinc and copper concentrates 



Concentrate and recoverable contained metals 



Deduction before payment calculation 



Remaining metal content 
paid for,' pet 



Less 



Zinc concentrate 
Zinc 

Cadmium 

Gotd 

BM» 

Lead 

Treatment charge 

Lead concentrate 
Lead 
Go*d 
Siver 
Copper 
Treatment charge 

Copper concentrate: 
Copper 
Gotd 

Treatment charge 
Cone Concentrate NAp Not applicable 



None 

do 

02 tr oz gold per dry ton cone 
3 tr oz silver per dry ton cone 

3 wt pet lead 

NAp 



1 wt pet lead 

02 tr oz gold per dry ton cone 

1 tr oz silver per dry ton cone . 

1 5 wt pet copper 

NAp 



1 wt pet copper 

02 tr oz gold per dry ton cone 

1 tr oz silver per dry ton cone 
NAp 



85 


$0.01 /lb. 


60 


$1 ,00/lb. 


75 


$2.50/tr oz. 


70 





50 





NAp 


$223.07/t cone 


94 


$0.05/lb 


95 


$5 00/troz. 


95 


$0 20/troz 


60 


$0 40/lb. 


NAp 


$156.79/tconc 


97.5 


$0.14 lb 


95 


$5.00/tr oz. 


95 


$0.25/tr oz. 


NAp 


$99 91/tconc. 



At January 1982 prices (table 1) 



16 



was compiled from these responses. It must be stressed that 
actual negotiated terms could vary widely from this schedule; 
however, it was compiled to represent average rates. 

Table 16 demonstrates how this generalized smelter 
schedule is applied to a particular concentrate. It can read- 
ily be seen from the calculations in table 16 that mines receive 
only a portion of the gross value of the metal contained in 
the concentrates, in this case 64 pet. It is also apparent that 
if the concentrate contained no silver values, the percentage 
of metal value paid for by the smelter would only be 46 pet. 

As illustrated in table 16, mines do not receive payment 
for all of the contained metal content in the concentrates. As 
stated in reference 24: "The actual revenue received by the 
mine can vary from as little as 45 pet to more than 95 pet 
of the gross value of metal contained in the concentrate. 
Smelter terms are, therefore, a significant factor in the estima- 
tion of potential revenues from any new mining venture." It 
should be noted that the operations with higher concentra- 
tions of precious metals, which are located in NMVT deposits, 
generally receive a higher percentage of the gross metal value 
back from the smelters-refineries. 

For the purposes of this investigation, the smelter treat- 
ment charge is handled as an operating cost incurred by the 
mine, rather than a debit against metal value given at the 
smelter, as is the actual practice. Either way, the treatment 
charge is a cost that must be paid by the mine for process- 
ing the concentrates. The costs to the mines for postmill proc- 
essing of all concentrates range from 10 to 85 pet of the 
average total operating costs (i.e., mine and mill operating 
costs, transportation, and smelter charges) at the properties 
evaluated. The majority of smelter costs ranged from 20 to 
50 pet of the average total operating cost. However, this does 
not apply to operations that have a unique situation such as 



Table 16. — Application of the generalized smelter schedule 

(75 pet lead concentrate containing 40.5 tr oz per ton silver) 



Cost per 
metric ton 

$383.38 
+ 323.88 

707.26 
-156.79 

550.47 



Paid for by smelter:' 

For lead 

For silver 

Total for metals 

Less treatment charge 

Total 

Contained metal value: 2 

Lead 496.04 

Silver +358.48 

Total 854.52 

1 Values from table 1 5, prices from table 1 . 

Lead = (75-1 wtpct)(0.94)($0.30-$0.05/lb)(2,204.6lb/t). 

Silver = (40.5- 1 troz/ton)(0.95)($8.03-$0.20/troz)(1.1023ton/t). 

2 Prices from table 1 . 

Lead = (75 wt pct)($0.30/lb)(2,204.6 Ib/t). 

Silver = (40.5 tr oz/ton)($8.03/tr oz)(1. 1023 ton/t). 



exceptionally high or low mining, milling, or transportation 
costs, or when the concentrate grade is unusually low. 

Use of the generalized smelter schedule includes several 
assumptions: (1) none of the concentrates are tolled, a situa- 
tion where, after processing (24), "all or part of the metal con- 
tained in the concentrate is returned to and marketed by the 
mine," (2) all of the concentrates are assumed to be accept- 
able feed for any of the facilities, and (3) none of the concen- 
trates contain deleterious material of sufficient quantity to 
incur a penalty. 



OPERATING COSTS 



The total operating cost of a mining project is a combina- 
tion of direct and indirect costs. Direct operating costs include 
operating and maintenance labor and supplies, supervision, 
payroll overhead, insurance, local taxation, and utilities. The 
indirect operating costs include technical and clerical labor, 
administrative costs, maintenance of facilities, and research. 

According to this evaluation, long-run operating costs for 
the large, efficient mines in the Viburnum Trend are com- 
petitive at current market prices. However, the lead and zinc 
operations in other parts of the country generally have much 
higher operating costs owing to the depth and structure of 
the ore bodies. These other operations often must depend 
upon byproduct revenues from precious metals, particularly 
silver, to offset the high cost of production. Figure 6 is a bar 
graph depicting the relationship between operating costs (the 
negative portion) and byproduct revenues (the positive por- 
tion), with each bar representing an individual operation. 

This bar graph shows that operations with higher 
byproduct revenues tend to have higher operating costs as 
well. Those operations with the highest byproduct revenues 
are able to offset all or a substantial portion of the operating 
costs, thus improving their competitive position relative to 
those operations that do not benefit from byproduct revenues. 
This byproduct revenue-operating cost relationship can be 
further characterized by the type of deposit. Eighteen of the 
twenty-four NMVT deposits are represented in the first 20 
bars, which demonstrates why a nonproducing NMVT deposit 
may have a better chance at being developed in the future 
than a MVT deposit with similar, or even superior lead or zinc 
grades. 

Table 17 shows a percentage breakdown of total 
operating costs into mining and milling operating cost, 
transportation cost from the mill to the smelter, and smelting- 
refining treatment charges experienced by each present and 
proposed operation. The table indicates that the major por- 



tions of the operating costs are incurred during the mining 
and postmill processing stages. 

Of the 67 operations evaluated, 55 were found to have 
mining operating costs ranging between 30 and 60 pet of the 
total operating cost for that operation. Smelter treatment 
charges ranged between 20 and 50 pet of the total for 62 of 
the operations. Milling operating costs were less than 30 pet 
for 61 operations, and transportation costs accounted for less 
than 10 pet of the total operating costs for 52 of the deposits 
evaluated. For all but two of the deposits, transportation costs 
were 20 pet or less of the total operating cost. 

It should be noted that the transportation costs were 
generally estimated from the mill to the nearest postmill proc- 
essing facility and that a common smelter schedule was 
developed and applied to all facilities. The use of a common 
smelter schedule does not take into account the actual varia- 



Table 1 7. — Breakdown of operating costs showing the number of 
operations in each percentage category 1 






Percent of 
total 



Mining 



Milling 



Transpor- 
tation 



Smelter 
charges 



0to10 7 52 

10 to 20 3 32 13 2 

20 to 30 6 22 1 16 

30 to 40 26 6 1 22 

40 to 50 20 24 

50 to 60 9 2 

Over 60 3 1 

Total _ 67 67 67 67 

1 Percentages of the total operating costs determined for each individual 
operation. The table is made up of data for both lead and zinc properties, as no 
difference was discernable between the two. 



17 



3.00 



2.50 



2.00 



1.50 



1.00 



50 



.00 



.50 



1.00 



1.50 



2.00 



2.50 



ESS 



KEY 
Smelter charge 
Mine operating cost 
Mill operating cost 
Transportation cost 




3.00 <- 
FIGURE 6.— Byproduct revenues and operating costs per pound of primary lead or zinc recovered at each operation. 



tions in the negotiated contract terms that occur within the 
industry. The range of smelter-refinery operating costs be- 
tween 20 and 50 pet of the total is probably a good represen- 
tation, however, the actual distribution within these ranges 



may vary. Transportation costs could vary if concentrates 
were shipped by alternative methods or to more distant 
facilities, and this could have an impact on the overall 
operating cost of an operation as well. 



CAPITAL COSTS 



Capital expenditures were calculated for exploration, ac- 
quisition, development, mine plant and mine equipment, and 
for constructing and equipping the mill. The capital expen- 
ditures for the different mining and processing facilities in- 
clude the costs of mobile and stationary equipment, construc- 
tion, engineering, infrastructure, and working capital. 

The initial capital costs for producing or past producing 
mines, and developed deposits have been depreciated ac- 
cording to when the investment was actually made, and the 
undepreciated portion was treated as a capital investment 
in 1982, the first year of the evaluation. Reinvestments will 
vary according to capacity, length of production life, and age 
of the facilities. 

Initial mine and mill capital investments, based mainly 
on the Eastern Tennessee and Kentucky zinc deposits, range 



from $165 to $265 per annual metric ton of capacity, with the 
majority being just above $200 per metric ton. These ranges 
are for proposed underground mines that have had no 
previous development work and will require only minimal ex- 
penditures on infrastructure. Infrastructure costs can be quite 
high in remote, undeveloped areas of the country, and mines 
that will require substantial infrastructure expenditures, such 
as those in Alaska, may require up to 2.5 times more initial 
capital investments per annual metric ton of capacity. Total 
initial capital investments for some of the undeveloped 
deposits may range as high as $700 million. 

After production parameters and costs for the develop- 
ment of domestic lead and zinc deposits were established, 
the SAM was used to perform various economic evaluations 
pertaining to the availability of domestic lead and zinc. 



18 



AVAILABILITY OF DOMESTIC RESOURCES 



Many factors contribute to the economic status of a 
deposit. Capital expenditures vary from deposit to deposit 
depending upon the mining and milling methods used as well 
as the annual capacity. The cost of transportation and 
smelting-refining, although often out of the direct control of 
the mine, will directly impact the total cost of production of 
the refined product to various degrees. The revenues 
generated from the byproducts recovered will vary according 
to the smelter schedule, and the impact of byproduct 
revenues, or the lack thereof, often determines the make-or- 
break point for some operations. This is especially true for 
the NMVT deposits, most of which are located in the Western 
United States. 



PRIMARY LEAD 

The 14 mines and deposits evaluated as primary lead 
operations have in situ demonstrated resources totaling 315.3 
million t, which contain 20.4 million t of lead. A total of 17.5 
million t of lead could potentially be recovered from these 
operations, and an additional 5.6 million t of lead could be 
recovered as a byproduct from primary zinc operations. This 
results in a total of 23.1 million t of recoverable lead from the 
mines and deposits evaluated for this study. 

Economic evaluations were performed on the 14 primary 
lead deposits. Nine of these deposits were producing as of 
January 1, 1982, and the determined weighted average of 
their total costs was $0.31 per pound of lead. Seven of the 
nine producers are located in the Southeastern Missouri Lead 
District and they account for 96 pet (15 million t) of the poten- 
tially recoverable lead from the producing operations. The 
remaining 4 pet (581,000 t) is recoverable from mines with 
heavy concentrations of precious metals, where the revenues 
generated from other commodities usually allow for the 
recovery of lead at little or no additional cost. 

A comparison of the weighted average of the total cost 
of production per pound of recovered lead from currently pro- 
ducing operations to the January 1982 market price of $0.30 
per pound, indicates that many of the domestic lead opera- 
tions can produce competitively over the long-run at current 
market prices and still achieve the stipulated 1 5-pct DCFROR. 
Economic evaluations determined that six of the nine pro- 
ducing operations had long-run total costs of $0.32 per pound 
of lead, or less. This accounts for 59 pet (10.3 million t) of 
the lead potentially recoverable from all 14 primary lead 
operations. 

Evaluations performed on the five nonproducing deposits 
determined a weighted average of their total costs of $0.56 
per pound of lead. All but one of these deposits is located 
in Missouri. Figure 7 shows the total availability curve for the 
14 selected primary lead mines and deposits, and illustratas 



3 6 

a. 

^ -3 



<n .2 
o 



1 1 1 1 r 

Costs include 15-pct rote of return on 
invested capital 



r 



H O 2 4 6 8 IO 12 14 16 

TOTAL RECOVERABLE LEAD, IO*t 

FIGURE 7.— Cost and total availability of primary lead. 



K 4 



e o 



r> II992 



nr~ 



IOO 200 300 400 500 

ANNUAL RECOVERABLE LEAD, I0 3 t 



FIGURE 8.— Cost and annual availability of primary lead for 
selected years. 



\0-$Q4O 



0-$O.3O 



YEAR 

FIGURE 9.— Annual availability of producing primary lead 
operations for selected price ranges. 



that 94 pet (16.4 million t) of the 17.5 million t of recoverable 
primary lead is potentially available at or below a long-run 
total cost of $0.40 per pound. 

Figure 8 shows the annual potential production of lead 
available for 1982, the base year of the investigation, and for 
10 and 20 yr into the future. Under the assumptions made 
for this investigation, potential production levels could remain 
fairly constant over the next 20 yr at a price-cost structure 
between $0.30 and $0.40 per pound of lead. This point is fur- 
ther illustrated by figure 9, which shows the annual produc- 
tion levels for the nine producing operations over the next 
20 yr at the price ranges of $0.30 per pound and below, and 
$0.40 per pound of lead and below. Although not shown on 
the curve, a small amount of lead (12,000 1) had long-run total 
costs above $0.40 per pound. 



PRIMARY ZINC 

The 53 primary zinc mines and deposits include total in 
situ demonstrated resources of 1 .04 billion t containing 49.2 
million t of zinc. Potentially, 39.9 million t of zinc could be 
recovered from the primary zinc deposits, and an additional 
2.4 million t could be recovered as a byproduct from primary 
lead operations. This results in a total of 42.3 million t of poten- 
tially recoverable zinc. 

There were 1 6 producing zinc deposits as of January 1 , 
1982, and economic evaluations determined their total costs 
at a weighted average of $0.61 per pound of zinc, as com- 
pared to the January market price of $0.42 per pound of zinc. 
This (market price-total cost) difference contributed to a 
number of operations closing or going on a temporary standby 



19 



1 1 1 ! 

Corts mckide 15-pct rate erf return on 
invested copitol 




W IS 20 23 30 33 40 

TOTAL RECOVERABLE ZINC, IO*t 

FIGURE 10.— Cost and total availability of primary zinc. 



S i.oo- 




I00 I50 200 250 300 

ANNUAL RECOVERABLE ZINC, I0 3 t 

FIGURE 1 1 .—Cost and annual availability of producing primary 
zinc operations for selected years. 



status during 1981 and 1982. Only 1 .2 pet (483,000 t) of the 
potentially recoverable zinc was available below a long-run 
total cost of $0.44 per pound of zinc. The evaluations for the 
37 nonproducers resulted in a weighted average of their total 
costs of $0.98 per pound of zinc, which is 2.3 times the 
January 1982 price. 

Figure 10 shows that of the nearly 40 million t of 
recoverable primary zinc, 80 pet (31 .9 million t) is potentially 
recoverable at costs between $0.50 and $1 .25 per pound of 
zinc. Thus the majority of zinc is available from mines and 
deposits with price-cost structures that are not economic 
under present conditions. In order for production to begin from 
many of these operations, there would need to be substan- 
tial increases in metal prices, improvements in mining and 
processing technology, some form of guaranteed financial 
backing, or possibly a combination of these alternatives. 

Figure 1 1 shows potential annual production levels for 
producing operations for the base year, 1982, and for 10 and 
20 yr into the future. Depletion appears to occur quickly; 
however, reported resource values for several of the mines, 
particularly NMVT mines in the western part of the country, 
could remain fairly constant over the years, and actual deple- 
tion of those deposits will probably occur much more slowly 
than indicated in figure 1 1 . This is because some operations 
delineate resources sufficient for only a few years of produc- 
tion ahead of their current mining position, thus the resources 
currently defined appear to become depleted in the next 5 
to 10 yr. However, there is a good probability that additional 
resources exist to allow for continued operation beyond the 
reported 5 to 10 yr. 

Figure 12 shows the proposed potential annual produc- 
tion levels for nonproducing mines and deposits for 5, 10, 
and 20 yr into the future. Production levels were attained 
assuming that all preproduction developing work was to have 
begun in 1982 (base year, N), and thus a number of opera- 




200 400 600 800 1,000 

ANNUAL RECOVERABLE ZINC, I0 3 t 

FIGURE 12.— Cost and annual availability of nonproducing 
primary zinc operations for selected years. 



tions would have come on line in the next 5 yr and could begin 
to pick up for the decline experienced by the current produc- 
ing operations. As seen in this curve, annual production levels 
from primary zinc operations would peak in iO yr. Thereafter, 
production would begin to decline unless additional resources 
were located, technologic improvements were made to allow 
for the processing of lower grade material, or other alternative 
sources were developed, such as the recovery of metals from 
geothermal brines that is currently being tested by the Bureau 
(25). It should be kept in mind that the total cost of produc- 
tion for most of the nonproducing operations is well above 
current economic levels and actual production from these 
mines and deposits will depend on a number of economic 
and technologic factors, and growth and declines in produc- 
tion rates will probably be much more gradual. 



SENSITIVITY ANALYSES 



Production costs for primary lead and zinc are influenced 
by a number of factors. The following sections will discuss 
the impact that varying the stipulated 15-pct DCFROR has 
on the availability of lead and zinc, as well as the impact of 
fluctuating byproduct prices, and the impact of increased 
smelter charges. 



IMPACT OF VARYING DISCOUNTED-CASH- 
FLOW RATE OF RETURN 

As previously defined, the DCFROR is the rate that 



makes the present value of all current and future revenues 
equal to the present value of all current and future costs. For 
this study, a constant minimum rate of return of 15 pet was 
specified. This rate was considered sufficient to attract new 
capital to the industry. In order to show the impact that the 
15-pct DCFROR had on the long-run total costs and availabil- 
ity of primary lead and zinc from the 67 mines and deposits 
investigated, they were evaluated at a breakeven (0-pct) 
DCFROR where all investments are recovered but no return 
was realized. 

Figure 13 illustrates the differences between the 
availability curves for primary lead at the breakeven and 



20 



(0-pct) DCFROR level than at the specified 15-pct level. Nine 
of the fourteen primary lead operations were producing at 
the time of this evaluation and their price-cost structures were 
not impacted significantly by varying the rate of return on 
investment. 



Costs include 15-pct rate of return on 
invested capital .. EY 

I5 _ pct discounted-cash-flow rate of return 

O-pct discounted-cash-flow rate of return 



r- 



* 6 8 IO 12 14 

TOTAL RECOVERABLE LEAD, I0 6 t 



FIGURE 13.— Cost and total availability of primary lead at 0-pct 
and 15-pct DCFROR. 



15-pct DCFROR. According to the results, specifying the 
DCFROR of 15 pet had little impact upon the total cost of 
production for the lead operations. It should be noted that 
9 of 16 of the primary lead operations are currently produc- 
ing. The initial capital for the producing operations has been 
recovered, leaving a much smaller investment base earning 
the specified DCFROR. Conversely, note the increase in the 
total costs of the 15-pct DCFROR curve on the right side of 
the curve where currently nonproducing deposits are 
represented. 

Figure 14 shows that achieving the specified 15-pct 
DCFROR had a greater effect on the total costs for primary 
zinc operations. The majority of recoverable primary zinc 
could be available between $0.40 and $0.75 at the breakeven 
level, which is substantially different from the $0.50 to $1 .25 
range required at a 15-pct level. However, it should be 
stressed that 37 of the 53 primary zinc mines and deposits 
are not currently producing and most would have large initial 
capital investmentsto recover, and consequently, a relatively 
large investment base earning the specified DCFROR. 

In summary, the primary zinc operations showed the 
largest increase in total costs when attaining the specified 
15-pct DCFROR. The 37 nonproducing zinc operations had 
significantly lower price-cost structures at the breakeven 



IMPACT OF BYPRODUCT PRICE CHANGES 

The presence of recoverable byproducts enhances the 
economic availability of the primary product. In order to show 
the impact of changes in byproduct revenues upon the total 
cost of the primary commodity, a sensitivity analysis was per- 
formed holding all cost constant and substituting average 
1980 commodity prices for the evaluation value prices of 
January 1982. For the purposes of this evaluation, all 
recoverable byproducts were sold and byproduct revenue 
credits were applied according to the generalized smelter 
schedule discussed earlier. Average 1980 prices were used 
because they represent wide price fluctuations, with some 
commodity prices being higher and others lower than the 
January 1982 prices, some by significant amounts. Any other 
set of alternative prices would impact individual mines dif- 
ferently, but the importance of byproduct prices can be seen 
clearly in this analysis. Table 18 lists the January 1982 and 
the average 1 980 prices that were used in the analysis. Note 
that while zinc prices have remained relatively constant over 
the years, they were down in 1980. Lead prices, on the other 
hand, fluctuate widely and were relatively high during 1980. 

Figures 15 and 16 show the changes in the total cost 
of production, after credit for byproduct revenues, that oc- 
cur when average 1980 commodity prices are substituted for 
January 1982 prices. The total cost for primary zinc and lead 
showed the largest increase from average 1980 to January 
1982 commodity prices for those operations in NMVT deposits 
that recovered significant quantities of byproducts or 



Table 18.— Commodity prices used in byproduct sensitivity 
analyses 



Commodity 

Barite per ton . 

Cadmium per lb. 

Copper per lb. 

Fluorspar pert. 

Gold pertroz. 

Iron (pellets) per Itu. 

Lead per lb . 

Limestone per t . 

Silver per tr oz . 

Zinc per lb. 



January 
1982 



Average 
1980 



105.00 


$70.00 


1.40 


2.84 


.79 


1.00 


165.00 


109.00 


384.12 


596.00 


.81 


.75 


.30 


.42 


4.13 


3.35 


8.03 


18.00 


.42 


.37 



Costs include 15-pct rate of return on 
invested capital «EY 

1 5pct discounted-cash-flow rate of return 

0-pct discounted-cash-flow rate of return 





IO I5 20 25 30 

TOTAL RECOVERABLE ZINC, I0 6 t 



FIGURE 14.— Cost and total availability of primary zinc at 0-pct 
and 15-pct DCFROR. 



Costs include 15-pct rate of return on 

invested capital 

KEY 

January I982 commodity prices 

Average I980 commodity prices 





IO 15 20 25 30 35 40 

TOTAL RECOVERABLE ZINC, I0 6 t 

FIGURE 15.— Cost and total availability of primary zinc using 
average 1980 and January 1982 commodity prices. 



21 



| ■- 

5 9- 

CM 

g 

3 6- 

§ 5- 

a A - 
at 

u, 5- 

fc 2- 



Chide Jr.* 'are ot return on 
iwea ted capital 

KEY 

Jormory I982 commodity prices 

Average 1980 commodity prices 



r 



TOTAL RECOVERABLE i_EAD, 10^ 

FIGURE 16.— Cost and total availability of primary lead using 
average 1980 and January 1982 commodity prices. 



coproducts such as copper, silver, and/or gold, which were 
experiencing higher prices during 1980 than in January 1982. 

Figure 15 illustrates that the greatest impact from 
byproduct revenues occurs in those primary zinc operations 
with a total cost between $0.50 and $1 , and mostof the ton- 
nage from these operations is located in NMVT deposits. Ap- 
proximately 67 pet of the operations in this price range were 
producing when the byproduct prices were higher, however, 
as of January 1 , 1982, only 37 pet of them were still produc- 
ing. Since January 1 982, a number of additional mines have 
gone on standby status or have closed indefinitely. 

Figure 16 indicates that byproduct or coproduct prices 
have very little impact upon the total cost of production for 
most primary lead operations. This is because 11 of the 14 
primary lead operations are located in MVT deposits and 
generally recover only a minor amount of byproducts. 

A decrease in byproduct revenues resulted for some of 
the primary zinc operations when average 1980 prices were 
substituted for the commodities such as iron, fluorite, barite, 
and agricultural limestone, which have increased since 1980. 
This decrease in byproduct revenues caused an increase in 
the total cost of production for zinc operations that recovered 
those commodities. The price for zinc was also down in 1980, 
and the total cost of production also increased for two of the 
primary lead operations that recovered significant amounts 
of zinc. These cost reversals are shown in the bar graphs 
in figures 17 and 18, which illustrate the amount of byproduct 
revenues generated at 1980 and 1982 commodity prices in 
terms of dollars per pound of recovered primary commodity. 
Note that not all operations are represented in these figures; 
those without byproducts and those with no change in 
revenues were not included. 

It should be kept in mind that the evaluations were done 
at a specific point in time using long-run constant costs and 
commodity prices, and therefore reflect the relative costs and 
commodity prices that prevailed at that time. For deposits with 
recoverable byproducts, sensitivity analyses are very impor- 
tant to a complete evaluation. 

The total cost for an undeveloped primary zinc deposit 
located in a NMVT deposit and recovering precious metals 
as byproducts, dropped an average of $0.10 per pound of 
zinc when average 1980 commodity prices were substituted. 
Primary lead operations are mostly located in MVT deposits 
and recover only small amounts of byproducts from these 
deposits. The total cost of production for some of the primary 
lead operations dropped $0.02 to $0.03 per pound of lead 
and the total cost for the operations that recovered signifi- 
cant quantities of zinc actually increased by a cent or two. 
The variations shown by this evaluation could have had other 
results with a different set of commodity prices, and varia- 
tions in commodity prices in the future may affect the 
economic attractiveness of a number of the mines and 
deposits evaluated. 



3.50 r 



« 3. DO- 
'S 



2.50 



2.00 



n 



1.50 



1.00 



D 
O 
BE 
a. .50 

> 

CO 



.00 




KEY 

■I 1980 
V77X 1982 



12 3 4 5 6 

PROPERTIES 



FIGURE 17.— Primary lead byproduct revenues below $3.50 
per pound of recovered lead, for selected operations, at average 
1980 and January 1982 commodity prices. 



3.50 r 



■ 3.00- f 
5 % 



2.50 



O 

0L 

£200 



Si 1.50 

> 

111 

K 

o 1.00 

Q 

o 

K 

£ .50 

m 



.00 L 






I 



KEY 

WM 1980 
^ 1982 



i 






■ i 
li 




2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 
PROPERTIES 



FIGURE 18.— Primary zinc byproduct revenues below $3.50 per 
pound of recovered zinc, for selected operations, at average 1980 
and January 1982 commodity prices. 



IMPACT OF INCREASED POSTMILL 
PROCESSING CHARGES 

Postmill processing charges are difficult to predict, but 
are crucial in a property evaluation. As discussed in the 
"Operating Costs" section, smelter charges ranged from 20 
to 50 pet of the total operating cost for 62 of the 67 opera- 
tions evaluated. This area of cost is subject to change as a 
result of supply and demand, and the smelter charges are 



22 



often out of the direct control of the mining operation itself. 
Also, since a common smelter schedule was used for the 
evaluations, it is possible that smelting costs for any particular 
operation could vary substantially from that assumed for the 
evaluation. For these reasons, the smelter treatment charges 
were arbitrarily increased by 50 pet for all operations in order 
to analyze the impact on the long-run total costs and availa- 
bility of primary lead and zinc from the mines and deposits 
included in this evaluation. 

Figures 19 and 20 illustrate that the increased smelter 
charges increased the total cost of production fairly equally 
for most operations. The lead operations were a little more 
sensitive overall than the zinc operations, because the ma- 
jority of lead operations are producing and capital costs are 
a lower percentage of total costs, while smelter treatment 
costs are a higher percentage, thus making producing opera- 
tions more sensitive to change than their nonproducing 
counterparts. The average total cost of production for lead 
operations increased between $0.07 and $0.09 per pound 
of lead. On a percentage of total cost basis, the producers 
would feel the greater impact. The overall increase in total 
cost is significant (23 to 29 pet) when compared to the January 
1982 market price of $0.30 per pound of lead. The January 
market price of zinc was $0.42 per pound and the increase 
caused by the higher smelter costs averaged between 24 and 
36 pet of the market price ($0.10 to $0.15 per pound of 
recovered zinc), and again the producers would feel the 
greater impact. 



i 1 1 1 r 

Costs include 15-pct rate of return on 

invested capital 

KEY 

Study-value smelter charges 

50-pct-higher smelter charges 



r 



4 6 8 10 12 14 16 

TOTAL RECOVERABLE LEAD, I0 6 t 



FIGURE 19.— Cost and total availability of primary lead using 
the study value and 50 pet higher smelter treatment charges. 



o 1 .4 



Costs include I5"pct rate ot return on 
invested capital 

Study-value smelter charges 

50-pct-higher smelter charges y 

r 




IO 15 20 25 30 

TOTAL RECOVERABLE ZINC, I0 6 t 



In summary, because postmill processing charges are 
usually not in the direct control of the mining company, the 
actual cost to each operation will vary according to a number 
of factors. The producing operations were more sensitive to 
change in smelter treatment charges than their nonproduc- 
ing counterparts. The common smelter schedule used for this 
evaluation should be looked on as reference base, with actual 
terms varying above and below the scheduled rates. 



SUMMARY OF 
SENSITIVITY ANALYSES 

Table 19 illustrates the results of the three sensitivity 
analyses by showing the changes in the weighted average 
of the total costs for primary lead, by the nine producers, five 
nonproducers, and the total for the 14 sites for each of the 
sensitivity factors analyzed. Table 20 summarizes the same 
information for primary zinc operations. These tables show 
that producing operations were impacted the most by 
increased smelter charges, and operations not in production 
as of the study date were influenced most by the specified 
DCFROR. While byproduct prices were crucial for some of 
the individual operations, on average they were found to be 
not as influential as the other two factors in the sensitivity 
analyses. 

The majority of primary lead operations were in produc- 
tion, and lead was influenced most by the smelter charge in- 
crease. Zinc operations, on the other hand, were mostly non- 
producers, and also contained a higher percentage of NMVT 
deposits with byproduct revenues. For these reasons, primary 
zinc operations were most sensitive to the specified DCFROR, 
and also were far more sensitive to increased byproduct 
revenues than were the lead operations, most of which are 
located in MVT deposits. 

Table 19. — Weighted average of total cost of production for 
primary lead operations 

(Cents per pound of lead) 

_ Pro- Nonpro- Weighted 

ducers 1 ducers 2 average 

At 15-pct DCFROR 31.1 56.1 33.9 

At break-even (0-pct) DCFROR 30.4 42.6 31 .8 

Using average 1 980 byproduct prices at 

15-pct DCFROR 30.8 54.8 33.4 

Using 50-pct-higher smelter charges at 

15-pct DCFROR 40.2 65.0 42.9 

1 9 producing operations as of January 1, 1982. 

2 5 nonproducing operations include past producing mines, as well as 
developed and undeveloped deposits. 



FIGURE 20.— Cost and total availability of primary zinc using 
the study value and 50 pet higher smelter treatment charges. 



Table 20.— Weighted average of total cost of production for 
primary zinc operations 

(Cents per pound of zinc) 

_ . Pro- Nonpro- Weighted 

ducers' ducers 2 average 

At 15-pct DCFROR 61.0 98.0 94.1 

At break-even (0-pct) DCFROR 56.7 57.5 57.4 

Using average 1980 byproduct prices at 

15-pct DCFROR 61.3 91.7 88.5 

Using 50-pct-higher smelter charges at 

15-pct DCFROR 71.2 110.0 106.3 

1 16 producing operations as of January 1, 1982. 

2 37 nonproducing operations include past producing mines, as well as 
developed and undeveloped deposits. 



23 



SUMMARY 



Recent economic trends of higher costs and declining 
metal prices have caused the closure of several mines and 
smelting-refining operations during the last few years. The 
U.S. smelters operate at a cost disadvantage relative to many 
foreign smelters, due partly to a substantial difference in 
governmental policies among countries that produce lead and 
zinc for worldwide consumption. Many governments support 
their domestic nonferrous metals industries, while U.S. 

Kolicies such as price controls and environmental regulations 
ave put many domestic producers at a cost disadvantage (7). 



DEPOSIT 
CLASSIFICATIONS 

Of the 67 sites evaluated for this study, 43 occur in 
Mississippi Valley-type (MVT) deposits, which are members 
of the strata-bound carbonate-hosted category (22). The other 
24 mines and deposits occur in all of the remaining deposit 
types, referred to here as non-Mississippi Valley-type (NMVT) 
deposits. The 43 MVT sites account for approximately 98 pet 
of the total in situ primary lead resources and 67 pet of the 
total in situ primary zinc resources. 

The NMVT deposits evaluated contain a higher value of 
recoverable byproducts than do the MVT deposits. Higher 
byproduct revenues generated from NMVT deposits offset 
a portion of the production costs and could make the NMVT 
deposits more attractive for future development. Revenues 
generated by byproduct gold, silver, and copper may be 
substantial, and in some cases may be the determining fac- 
tor as to whether a particular deposit is exploited, or whether 
a partcular mine remains open. However, not all deposits, 
regardless of MVT or NMVT classification, contain gold, silver, 
or copper. 

There is also a difference in mining methods and costs 
that exist between MVT and NMVT deposits. The majority 
of the MVT deposits are mined using some form of room-and- 
pillar mining, with operating costs that are generally lower 
than those methods used to mine the NMVT deposits. 

PRIMARY LEAD 

The current (January 1982) price-cost structure for 
primary lead, as shown in this investigation, indicates that 
the majority of operations were producing competitively, as 
59 pet (10.3 million t) of all recoverable primary lead was 
available at or below a long-run total cost of $0.32 per pound 
of lead. The total cost of production for the nine producing 
lead mines was determined at a weighted average of $0.31 
per pound of lead, and the January 1982 market price for 
lead was $0.30 per pound. Economic evaluations performed 
on the mines and deposits not in production as of January 
1 . 1982, had a weighted average for their total costs of pro- 
duction of $0.56 per pound of lead. 

Included in this investigation was a total of 315.3 million 
t of in situ primary lead resources containing 20.4 million t 
of lead. Potentially, 17.5 million t of lead could be recovered 
from the 14 primary lead operations, and an additional 5.5 
million t of lead could potentially be recovered as a byproduct 
from 20 of the primary zinc operations. Thus, a total of 23 
million t of lead could potentially be recovered from 34 opera- 
tions, and the cumulative demand through the year 2000 has 
been forecasted at 13.3 million t of recovered lead (18). Pro- 
duction levels for primary lead could remain relatively con- 
stant for the next 20 yr for the price-cost structure between 
$0.30 and $0.40 per pound of lead, assuming continued pro- 
duction from already producing operations and development 
of additional deposits beginning in January 1982. 



SENSITIVITY ANALYSES RESULTS 
FOR PRIMARY LEAD 

Sensitivity analyses were performed on the 14 primary 
lead operations to determine the impact of several factors 
on the total cost of production. These analyses included the 
impact of the stipulated 15-pct DCFROR versus a breakeven 
(0-pct) DCFROR, the impact of byproduct revenues using 
average 1980 commodity prices versus the investigation 
values of January 1982 prices, and the impact of increasing 
smelter charges by 50 pet. 

Nine of the fourteen primary lead operations were pro- 
ducing, and these producing operations showed little effect 
from the DCFROR sensitivity analysis because their initial 
capital investments had been recovered. Increased byproduct 
prices also had little effect on the availability of primary lead, 
as 11 of the 14 sites were located in MVT deposits, which 
do not contain the high amounts of byproducts that NMVT 
deposits contain. 

The analyses revealed that only increased smelter 
charges had any real impact on the cost of production, and 
again this is because the majority of the lead operations were 
producing. Operating costs make up a larger percentage of 
the total cost of production for producing operations, and 
smelter costs are a substantial portion of these operating 
costs, between 20 and 50 pet for most operations. Increas- 
ing smelter charges by 50 pet increased the weighted average 
of the total cost for producing operations by nearly 30 pet, 
from $0.31 to $0.40 per pound of lead, while the long-run total 
cost for the nonproducing operations increased about 16 pet, 
from $0.56 to $0.65 per pound. 



PRIMARY ZINC 

The 53 primary zinc mines and deposits include 1.04 
billion t of in situ demonstrated resources containing 49.2 
million t of zinc. The total potentially recoverable zinc is 42.3 
million t from the mines and deposits evaluated, including 
the 2.4 million t of byproduct zinc available from the primary 
lead resources. Most of the resources are contained in mines 
and undeveloped deposits with price-cost structures that are 
higher than the January 1982 market price of $0.42 per pound 
of zinc, only 1 .4 pet (555,000 1) of the total recoverable zinc 
from primary zinc operations was available at or below a long- 
run total cost of $0.44 per pound of zinc. 

There were 16 producing zinc mines as of January 1, 
1982, and economic evaluations determined a weighted 
average of the total cost of $0.61 per pound of zinc. Due in 
part to the price-cost difference between these operations and 
the January market price, a number of mines closed or went 
on temporary standby status during 1982. The evaluations 
for the 37 nonproducers resulted in a weighted average of 
the total cost of $0.98 per pound of zinc, which is more than 
2.3 times the January 1982 market price of $0.42 per pound 
of zinc. 

The nearly 40 million t of recoverable zinc potentially 
available from the domestic primary zinc resources is more 
than adequate to meet the cumulative projected demand of 
10.7 million t of refined zinc through the year 2000, but the 
majority of the resources are available from currently non- 
producing mines and deposits (20). If preproduction for all 
nonproducing primary zinc deposits were to have begun in 
1982, and current producers were to operate at full capacity, 
total production would peak in 10 yr. After 10 yr, a number 
of currently producing and smaller nonproducing operations 
would begin to run out of resources and production levels 
would drop as depletion occurred. Actual production from the 
currently nonproducing mines and deposits would depend 



24 



on a number of economic and technologic factors, and either 
growth or declines in production rates would be much more 
gradual than assumed for this analysis. 

SENSITIVITY ANALYSES RESULTS 
FOR PRIMARY ZINC 

Sensitivity analyses were also performed on the 53 
primary zinc operations to determine the impact of several 
factors on the total cost of production. These analyses 
included the impact of the stipulated 15-pct DCFROR ver- 
sus a breakeven (0-pct) DCFROR, the impact of byproduct 
revenues using average 1980 commodity prices versus the 
evaluation values of January 1982 prices, and the impact of 
increasing smelter charges by 50 pet. 

The analyses revealed that the primary zinc operations 
appear to be more sensitive to changes in the assumptions 
underlying the evaluations than the lead operations. The zinc 
operations were quite sensitive to the level of prespecified 
DCFROR because 37 of the 53 operations were non- 
producers at the time of the evaluation. 

Byproduct revenues were also important to the 
economics of the zinc operations. A number of the primary 
zinc operations are located in NMVT deposits, and they de- 
pend on the revenues generated from byproducts to help 
meet the cost of production. As a result of using byproduct 
credits calculated at average 1980 commodity prices instead 
of January 1982 prices, the weighted average of the total 
costs for all zinc operations decreased by about 6 pet. The 
range of change in the individual mine's total cost due to 
byproduct credits was quite wide, with up to 85 pet higher 
total costs at January 1982 prices than at average f980 
prices. 

Although not nearly as important on average for zinc as 
for lead, a 50-pct increase in smelter charges still raised the 
weighted average of the long-run total cost of production for 
producing operations from $0.61 to $0.71 per pound of zinc 
(17 pet). The weighted average of the total cost of produc- 
tion for nonproducing operations rose from $0.98 to $1.10 
per pound (12 pet). 



DOMESTIC SMELTER 
CAPACITY 

Domestic zinc smelter capacity has been declining over 
the years, and this may be as critical to the U.S. position of 
self-sufficiency as the amount of domestic resources 
available. The 5-yr average (1977-81) domestic mine concen- 
trate production levels were 94 pet of primary (refined) lead 
production, and the import reliance was approximately 4 pet. 
Zinc, however, had average domestic mine concentrate pro- 
duction levels at 82 pet of the domestic refined (slab) zinc 
levels, but import reliance amounted to 62 pet. 

The domestic lead industry was found to be competitive 



at January 1982 market prices. The large, efficient, and often 
automated lead and secondary lead industry is well enough 
developed to provide over half of the current supply 
requirements. However, closure of the Bunker Hill smelter- 
refinery complex as well as overcapacity problems at a 
number of the domestic primary and secondary processing 
facilities may indicate that the domestic smelting-refining 
industry may not be able to maintain its current competitive 
position. A potential decline in capacity could be partially 
attributed to declining metal prices and costly environmental 
regulations that are more stringent domestically than in some 
of the other countries that compete with the United States 
(6-8). 

The current refinery capacity of 595,000 1 of lead per year 
is sufficient, but forecasts project that an additional 105,000 
t of annual capacity will be needed to meet demand re- 
quirements in the year 2000 if import levels of refined lead 
are to remain at their current low levels, or 205,000 1 of addi- 
tional capacity would be required to attain primary (refined) 
lead self-sufficiency (78). Additional capacity could be re- 
quired if current capacity levels decline. The cumulative de- 
mand through the year 2000 is forecast at 13.3 million t of 
lead. Although production levels would have to be increased, 
the resources evaluated could recover an estimated 17.5 
million t of lead over their projected lives, and 90 pet 
(16.4 million t) could potentially be recovered at or below a 
cost of $0.40 per pound of lead. 

The decline in domestic zinc self-sufficiency over the 
years has been due to the low zinc grades of domestic mines 
and the increasing cost of producing from them. The market 
value of zinc has not kept up with the increasing cost of pro- 
duction, and the result has been the closure of a number of 
domestic zinc mining operations (8, 12). 

Projected annual demand for refined slab zinc through 
the year 2000 has been forecasted at 1 .05 million t, while cur- 
rent capacity is only 390,000 t {20). The projected annual 
domestic mine capacity has been estimated at approximately 
640,500 t of zinc based on continuing high import 
dependence; however, maintaining the current capacity could 
be difficult in view of the low utilization levels that are 
precipitating a number of cutbacks and closures in the 
domestic zinc industry. 

With the supply of domestic zinc feed material declin- 
ing, domestic smelters have had to import concentrates to 
meet their needs, or shut down (8-9). This has been an ex- 
pensive alternative because many countries will produce and 
export the final products, such as slab zinc, at prices below 
their U.S. counterparts who have to add the cost of import- 
ing foreign concentrates to their cost of processing. The com- 
binations of domestic zinc smelters having to purchase 
foreign concentrates, the high cost of modernizing and 
operating the older facilities that predominate in the domestic 
zinc smelting industry, and the cost of environmental regula- 
tions, particularly for the lead industry, have all presented 
serious obstacles to the maintenance of the domestic lead 
and zinc industries. 



REFERENCES 



25 



1. Jolly, J. H. Zinc. Ch. in BuMines Minerals Yearbook 1981, v. 1, 
pp. 897-925. 

2. Rathjen, J. A., and W. D. Woodbury. Lead. Ch. in BuMines 
Minerals Yearbook 1981, v. 1, pp. 509-536. 

3. Davidoff, R. L. Supply Analysis Model (SAM): A Minerals 
Availability System Methodology. BuMines IC 8820, 1980, 45 pp. 

4. Rathjen, J. A. Lead. Sec. in BuMines Mineral Commodity Sum- 
maries 1982, pp. 84-85. 

5. Woodbury, W. D. Lead. Sec. in BuMines Mineral Commodity 
Summaries 1983, pp. 86-87. 

6. International Minerals/Metals Review 1980. United States, 
Primary Metals. McGraw-Hill Publ., Washington DC, 1980, pp. 
321-348. 

7. Everest Consulting Associates, Inc. (Princeton Jet., NJ), and 
CRU Consultants. Inc. (New York). The International Competitiveness 
of the U.S. Non-Ferrous Smelting Industry and the Clean Air Act. 
Ch. 4, 6. Apr. 1982. 

8. Kendrick, J. W. Testimony of J. W. Kendrick, President, Bunker 
Hill Co., before U.S. House of Representatives Subcommittee on 
Mines and Mining, Denver, CO, Nov. 10, 1981 , 1 1 pp.; available upon 
request from C. C. Kilgore, BuMines, Denver, CO. 

9. Mining Engineering. Efforts Made To Keep Bunker Hill Open. 
V. 33, Nov. 1981, p. 1559. 

10. Cammarota, V. A., Jr. Zinc. Sec. in BuMines Mineral Com- 
modity Summaries 1982, pp. 174-175. 

11. Jolly. J. H. Zinc. Sec. in BuMines Mineral Commodity Sum- 
maries 1983, pp. 174-175. 

12. Engineering and Mining Journal. The British Won the First 
Battle of Bunker Hill; Nobody Won the Second. V. 183, Mar. 1982, 
pp. 59, 63. 

13. . End of an Era in Idaho— The Closing of Bunker Hill 

Operations. V. 182, Oct. 1981, pp. 35-43. 

14. Mining Engineering. US and International Mineral News Briefs. 
V. 32, Jan. 1980, p. 17. 

15. Engineering and Mining Journal. St. Joe Will Develop Pierre- 
pont Zinc Mine and Reactivate Monaca. V. 181, Sept. 1980, p. 13. 

16. Metals Week. St. Joe Will Reactiviate Monaca Smelter. V. 51 , 
No. 34, Aug. 25, 1980, p. 2. 

17. U.S. Geological Survey and U.S. Bureau of Mines. Principles 



of a Resource/Reserve Classification for Minerals. U.S. Geol. Surv 
Circ. 831, 1980, 5 pp. 

18. Woodbury, W. D. Lead. BuMines Mineral Commodity Profile, 
1983, 17 pp. 

19. Woodman, B. Cominco's Philosophies Could Be Model for 
Alaska Mining Development. Alaska Constr. & Oil, v. 23, No. 9, Sept. 
1982, pp. 24-32. 

20. Jolly, J. H. Zinc. BuMines Mineral Commodity Profile, 1983, 
18 pp. 

21. Briskey, J. A. (U.S. Geological Survey). Written communica- 
tion, Mar. 1983; available upon request from S. J. Arbelbide, 
BuMines, Denver, CO. 

22. Briskey, J. A. and H. Wedow, Jr. Zinc Resources. En- 
cyclopedia of Materials Science and Engineering: Oxford Press, in 
press, 1983. 

23. Montag, L. R. (Union Pacific Railroad, Omaha, NE). Private 
communication, 1982; available upon request from S. J. Arbelbide, 
BuMines, Denver, CO. 

24. Lewis, P. J., and C. G. Streets. An Analysis of Base-Metal 
Smelter Terms. Pres. at 11th Commonwealth Mining and 
Metallurgical Congr., Hong Kong, May 1978, 15 pp.; available from 
the Institution of Mining and Metallurgy, London. 

25. Farley, E. P., E. L. Watson, D. D. MacDonald, R. W. Bartlett, 
and G. N. Krishnan. Recovery of Heavy Metals From High Salinity 
Geothermal Brine (contract J01 88076, SRI Int.). BuMines OFR 91-81, 
1980, 130 pp.; NTIS PB 81-222218. 

26. Ridge, J. D. Annotated Bibliographies of Mineral Deposits in 
the Western Hemisphere. Mem. Geol. Soc. America 131, 1974, 672 
PP- 

27. Gentry, D. W. Lead and Zinc Deposits in Colorado and Wyom- 
ing (Grant G0264005, CO School of Mines). CSM Project 361 , 1976, 
90 pp.; available for consultation at BuMines, Denver, CO. 

28. Foose, M. P. A Reinterpretation of the Structural and 
Stratigraphic Setting of the Balmat-Edwards Zinc Deposits, Northwest 
Adirondack Lowlands, New York. Econ. Geol., v. 75, No. 1, 1980, 
pp. 130-133. 

29. Mudrey, M. G., Jr. Zinc-Copper Resources of Wisconsin. Sell- 
ings Min. Rev., v. 67, Mar. 25, 1978, pp. 1, 16-19, 28. 



26 



APPENDIX A.— DOMESTIC LEAD AND ZINC OWNERSHIP INFORMATION 



Table A-1. — Domestic lead ownership information 



State and property Ownership 

Colorado: Bulldog Homestake Mining. 

Idaho: Lucky Friday Hecla Mining Co. 

Missouri: 

Boss-Bixby Getty Oil, AZCON, Hanna Mining. 

Brushy Creek Division St. Joe Minerals Corp. 

Buick AMAX Lead, Homestake Lead. 

Fletcher St. Joe Minerals Corp. 

Higdon-Bonne Terre Bunker Hill, St. Joe Minerals Corp. 



State and property Ownership 

Missouri— Con. 

Indian Creek St. Joe Minerals Corp. 

Magmont COMINCO AM., Dresser Ind. 

M'rlliken Kennecott Copper Corp. 

Viburnum No. 28 and No. 29 St. Joe Minerals Corp. 

Viburnum No. 35 Do. 

West Fork ASARCO. 

Utah: Ontario Noranda, United Park City Mines. 



Table A-2— Domestic zinc ownership information 



Sfafe and property 



Ownership 



Alaska: 

Arctic Kennecott Copper Corp. 

Greens Creek Noranda and others. 

Lik Houston Oil & Minerals, GCO 

Red Dog COMINCO. 

Colorado: 

Black Cloud ASARCO, Resurrection. 

Idar'ado Newmont Mining. 

Sunnyside Standard Metals. 

Idaho: 

Bunker Hill Bunker Hill, Gulf Resources. 

Star Morning Bunker Hill, Hecla Mining. 

Illinois: Minerva No. 1-Spivey Inverness Mining. 

Kentucky: 

Burkesville Project COMINCO, ASARCO, and others. 

Fountain Run St. Joe Minerals Corp. 

Maine: 

Bald Mountain Superior Oil Co. 

Kerr American-Blue Hill Kerr American Inc., Black Hawk. 

Montana: Butte District Zinc Anaconda Copper Corp. 

Nevada: 

Ruby Hill Mine Ruby Hill, Hecla, and others. 

Ward Mountain Gulf Oil, Silver King Mines. 

New Jersey: Sterling New Jersey Zinc Co. 

New Mexico: Pinos Altos Boliden Minerals, Exxon Minerals Corp. 

New York: 

Balmat St. Joe Zinc. 



Pierrepont 

Pennsylvania: Friedensville Mine. 
Tennessee: 

Beaver Creek •. 

Big War Creek 



Do. 
New Jersey Zinc Co. 

Do. 
Do. 



W Withheld, company proprietary information. 



Sfafe and property Ownership 

Tennessee— Con. 

Carthage Property St. Joe Minerals Corp. and others. 

Copperhill Cities Services Corp. 

Coy ASARCO Inc. 

Cub Creek New Jersey Zinc and others. 

Cumberland Jersey Miniere Zinc Co. 

Cumberland Deposit W. 

Cumberland Property St. Joe Minerals and others. 

East Gainesboro W. 

Gainesboro New Jersey Zinc and others. 

Gordonsville-Elmwood Jersey Miniere Zinc Co. 

Hartsville W. 

Hartsville Area COMINCO American, NL Industries. 

Idol New Jersey Zinc Co. 

Immel ASARCO Inc. 

Jefferson City Mine New Jersey Zinc Co. 

Lost Creek Do. 

New Market ASARCO Inc. 

Pall Mall ASARCO Inc. and others. 

Right Fork ASARCO Inc. 

Roaring River New Jersey Zinc Co., AMAX Inc. 

Stonewall Jersey Miniere Zinc Co. 

Young ASARCO Inc. 

Zinc Mine US Steel Corp. 

Washington: 

Boundary Dam-Metaline Falls Metaline, Washington Resources. 

Washington Zinc Unit Callahan Mining Corp. and others. 

Wisconsin: 

Crandon Exxon Minerals Corp. 

Crawhall-Elmo No. 3 Inspiration Mines. 

Pelican River Noranda Corp. 

Shullsburg-Bearhole Inspiration Mines. 



APPENDIX B.— MINES AND DEPOSITS EXCLUDED FROM THIS STUDY 



The mines and deposits listed below were excluded from 
this study because they did not contain sufficient quantities 
of lead and/or zinc to meet the criteria established for this 
evaluation. The criteria are explained in the "Introduction" 
section. 

Sfafe Property name 

Alaska Ground Hog Basin. 

Picnic Creek. 

Sum Dum. 

Sun Group. 

Arizona Bruce. 

Colorado Camp Bird. 

Eagle. 

Emperius. 
Idaho Couer Project. 

Galena 
Missouri La Motte. 

Madison. 
Nevada Caselton. 

Pan American. 

Prince. 



New Mexico Ground Hog. 

Hanover (Empire). 

Lynchburg. 

Princess. 
New York Edwards. 

Hyatt. 
Tennessee Cnucky Pike. 

Shiloh Prospect. 
Utah Burgin. 

Deer Trail. 

Lakeview. 

Mammoth. 

Mayflower. 

Pete's Tunnel. 

Spelter Tunnel. 

Tmtic Standard. 



Virginia 
Washington 



Trout Creek. 
U.S. and Lark. 
Volunteer Gulch Incline. 

Austinville-lvanhoe. 
Deep Creek. 
Pend Orielle. 



27 



APPENDIX C.— GEOLOGY NARRATIVES BY STATE 



The reader should refer to tables 4 and 6 in the main 
text for individual deposit resource tonnages and grades. 

ALASKA 

The Arctic massive sulfide deposit occurs in the Ambler 
Mining District in the Southwestern Brooks Range near the 
center of a northwest-trending belt of Paleozoic schistose 
rocks that outcrop on the Kalurivik arch. The trough-shaped 
stratiform volcanogenic deposit lies on the southwest limb 
of the arch. Major host rock units at the Arctic deposit are 
metarhyolites, metatuffs, and graphitic schists (21). 1 Zinc and 
copper-bearing minerals are dominant, with lead and silver- 
bearing minerals occurring in minor amounts. The district is 
potentially important as other massive sulfide deposits have 
been discovered since 1965. The Arctic deposit, as well as 
the other three Alaska deposits are non-Mississippi Valley- 
type (NMVT) deposits. 

The Greens Creek deposit is located in a National Monu- 
ment in the northeastern part of Admiralty Island. It is a strata- 
bound massive sulfide deposit occurring on the limb of an 
overturned anticline in an area of complexly folded volcanic 
rocks. The mineralogy is very complex, and several different 
ore types are present. Zinc, lead, gold, and silver-bearing 
minerals are the most important minerals. 

The Red Dog and Lik deposits occur in the Western 
Brooks Range in Paleozoic sedimentary rocks that are part 
of a complex series of thrust sheets. The deposits are 
stratiform massive sulfide deposits and lie within a shale unit 
(21). Zinc is dominant, with lesser amounts of lead and silver- 
bearing minerals occurring in the deposits. Not much explora- 
tion had been done in the Western Brooks Range prior to 
1970, but recent discoveries indicate that the area may be 
a major mineral province. In fact, the Red Dog deposit is one 
of the largest and richest zinc deposits known in the world. 

Although Alaska is an important potential producer of 
minerals, development of its resources is hampered by (1) 
a lack of infrastructure and its associated high cost, (2) ac- 
cess and transportation limitations, (3) restrictive land 
classification, and (4) the harsh climate, which causes opera- 
tional difficulties and potentially shortened mining seasons. 



COLORADO 

Three of the Colorado properties evaluated, the Sunny- 
side, Idarado, and Bulldog Mines, are located in the San Juan 
Mountains of southwest Colorado, an area covered by late 
Tertiary volcanics. The majority of the minerals in this area, 
including that of the three mines, occur marginal (adjacent) 
to calderas in faults and fractures, but "important ore bodies 
have been found in chimneys, mantos, stockwo-ks, and 
volcanic pipes" (26). 

Mineralized vein systems occasionally run for several 
kilometers and "may cut the entire volcanic series and the 
underlying sediments" (27). The underlying sediments also 
contain mineralized zones, and the amount of ore of this type 
still undiscovered in the area may be large because the 
sediments may lie under more than a kilometer of volcanic 
rock (26). 

At two of the sites, the precious metal content of the ores 
is much more imporant than that of lead and zinc. Although 
the proportions of specific minerals at each of the deposits 
vary considerably, the ores consist typically of lead, zinc, and 
copper minerals, along with significant amounts of silver and 
gold-bearing minerals. 



'Italicized numbers in parentheses refer to items in the list of references 
pr e cwtng the appendixes 



The Black Cloud Mine is located in central Colorado near 
Leadville, in an area covered by Paleozoic and Mesozoic 
sedimentary rocks that have been tilted, faulted, and frac- 
tured. Most of the Tertiary minerals in the western part of the 
Leadville District in the vicinity of the Black Cloud Mine oc- 
cur in replacement deposits in the Pre-Pennsylvanian Lead- 
ville and Dryer Dolomites. Significant deposits of minerals 
also occur in fault zones. Lead, copper, gold, zinc, and silver- 
bearing minerals are the major commercial minerals in the 
area. All Colorado sites occur in NMVT deposits. 



IDAHO 

The Lucky Friday, Star Morning, and Bunker Hill Mines 
are located in the Coeur d'Alene Mining District in 
metasedimentary rocks of the Precambrian Belt Supergroup. 
Many of the mines in the district lie near the Osburn Fault, 
a prominent structure that cuts through the area in a westerly 
direction. 

Minerals occur primarily in replacement veins, but 
mineral types are not uniform throughout the district. 
Ecoriomic minerals occur in the upper unit of the Revett 
quartzite, which is the horizon in which most of the mining 
has occurred. Complex fault systems related to the Osburn 
Fault occur throughout the area and "mineralization is most 
intense in the more faulted portions of the area, although the 
major faults are themselves essentially barren" (26). 

There is a very high probability that additional resources 
of lead and zinc exist in addition to those used for this evalua- 
tion because the vein structures continue at depth. It should 
be noted that mines in the area do not explore for additional 
resources in excess of about 5 yr worth of production. This 
has been the standard practice for many years and the 
published resource figures do not reflect the true potential 
of the district. 



ILLINOIS 

The Minerva No. 1 and Spivey Mines are located in the 
Illinois-Kentucky Fluorspar District, an area covering approx- 
imately 1 ,100 sq km and one of the most productive fluorspar 
districts in the world. The sites are in Mississippi Valley-type 
(MVT) deposits and occur in Mississippian sediments that 
have been deformed into a northwest-trending arch and then 
faulted. Most of the faults are steeply dipping, trend northeast, 
and are continuous for several kilometers. 

The deposits occur as either bedded replacement 
deposits (similar to the Minerva No. 1 Mine) or as vein 
deposits associated with the northeast-trending faults (similar 
to the Spivey Mine). The bedded deposits occur mostly in 
the top of the Ste. Genevieve Limestone, the Spar Mountain 
Sandstone Member of the Ste. Genevieve Limestones, and 
the top of the Downeys Bluff Limestone. The vein deposits 
are not as stratigraphically restricted as the bedded deposits, 
may be up to 10 m in width, and can be composed of pure 
fluorite. The important minerals are fluorite, sphalerite, 
galena, and barite. Lead and zinc resources, in addition to 
those evaluated, are associated with present and potential 
fluorite production from this district, but no estimate of the 
total amount available from this source was made. 



MAINE 

The Bald Mountain massive sulfide deposit is located in 
a belt of metamorphosed volcanic and sedimentary rocks that 
stretches from New Hampshire northeasterly into New 



28 



Brunswick, Canada. Copper and zinc occur in selected beds 
of siliceous rock that have a minor carbonate content. Gold 
and silver occur in minor amounts. Exploration in the area 
has increased substantially within the last 10 yr, and addi- 
tional deposits may be discovered in the belt in the future. 
The Kerramerican-Blue Hill property is located in an area 
of southeast Maine where the Paleozoic Ellsworth Schist 
comes in contact with granitic intrusions of Silurian or Devo- 
nian age. During the late 1800's some copper, lead, zinc, and 
a small amount of silver were extracted from mines in the 
region before mining was discontinued owing to low ore 
grades. At the Kerramerican property the minerals occur in 
a relatively pure quartzite. Zinc materials are the most im- 
portant, and occur in long, thin tabular bodies on the limb 
of a syncline. Chalcopyrite occurs throughout the deposit, but 
bodies high in copper are less frequent and much smaller 
than those containing zinc. All of the Maine sites occur in 
NMVT deposits. 

MISSOURI 

The lead deposits in southeastern Missouri occur on the 
flanks of a dome in a series of Upper Cambrian sedimentary 
rocks that encircle the St. Francois Mountains. Although there 
is some mineralized rock in other Paleozoic strata, most of 
the ore bodies occur in the brown dolomite of the Bonne Terre 
Formation. 

Ore deposits are strataform and the minerals generally 
occur either in replacement or disseminated deposits, 
veinlets, or fillings in open spaces. Although the deposits con- 
sist mostly of lead-bearing minerals, enough zinc is present 
for six of the seven producing mines to be included among 
the top zinc producers in the United States. Small amounts 
of nickel, cobalt, and cadmium also occur in the deposits. 

The Old Lead Belt, an area of extensive production in 
the past, is almost mined out, and development is now 
centered in the more recently discovered Viburnum Trend. 
All of the Missouri sites evaluated are located in the trend 
except the Higdon and Bonne Terre Mines, which are in the 
Old Lead Belt. Figure C-1 shows the locations of mines and 
deposits along the Viburnum Trend. Although the Indian 
Creek Mine is not located in the main portion of the trend, 
it is considered to be in an offset portion of the trend. Deposits 
that occur in the Southeastern Missouri District are— 



LEGEND 
J3J Mine and mill 

Mine, mill and smelter 
complex 
i^»i» Viburnum Trend 
@ Highway 



Bonne Terre 

Boss-Bixby 

Brushy Creek Division 

Buick 

Fletcher Division 

Higdon 



Indian Creek 

Magmont 

Milliken 

Viburnum No. 28 and No. 29 

Viburnum No. 35 

West Fork 



Traditionally, these deposits have been assigned to the 
MVT classification. However, recent studies comparing 
mineralogic and geochemical characteristics of the MVT 
deposits suggest that the Missouri deposits may not belong 
to the MVT category (21). Deposits in the Viburnum Trend 
are the only MVT deposits in this study that contain 
recoverable amounts of silver. In addition, deposits in the 
Viburnum Trend and the Old Lead Belt are the only MVT sites 
studied that contain recoverable amounts of copper. 



MONTANA 

The zinc resources evaluated occur in five old mine areas 
approximately 2 km northwest of the Berkeley open pit cop- 
per mine. The five areas are the Alice, Anselmo, Badger, Lex- 
ington, and Mountain Con Mines, all of which were closed 
as of January 1 , 1982. Although the Butte District is generally 
thought of as a copper district, 2.2 million t of zinc were pro- 
duced from 1880 to 1972. 




FIGURE C-1 .—Locations of lead operations in the Viburnum 
Trend in Missouri. 



The Late Cretaceous Butte Quartz Monzonite is the host 
rock for the deposits. Most of the resources occur within veins 
of the steeply dipping, east-west striking Anaconda vein 
system, with the mineralized portions of the veins extending 
for several hundred meters both horizontally and vertically. 

The mineralized rock in the Butte District is concentrically 
zoned, with different minerals dominating each of the zones. 
Copper minerals are predominant in the central zone in the 
area of the Berkeley open pit copper mine, and zinc is domi- 
nant in the intermediate and peripheral zones. Lead, copper, 
and silver-bearing minerals also occur in the intermediate 
zone. The five evaluated mines are located in this in- 
termediate zone. 



NEVADA 

The Ruby Hill deposit is located in the Eureka Mining 
District. The two most favorable stratigraphic horizons for 
mineralization in the district are the middle Cambrian 
Eldorado Dolomite and the middle to late Cambrian Hamburg 
Dolomite. Both dolomites host numerous replacement 
deposits. The area covered by the Ruby Hill evaluation is in 
between the Locan and Fad shafts. There, the Eldorado 
Dolomite is the host rock. Lead and zinc occur with associated 
gold and silver-bearing minerals, and the primary ores have 
been extensively oxidized by ground water. 

The Ward District is composed mainly of easterly dipping 
sediments that are underlain and intruded by Tertiary quartz 
monzonites. All past production has been from the Ely 
Limestone, but recent exploration has been directed at the 
deeper rocks. Mineralized rock has been found in the upper 
and basal portions of the Joana Limestone, the Upper 
Guilmette Limestone, and the Guilmette-Quartz Monzonite 
contact. In addition to lead and zinc, low grade copper- 
molybdenum mineralized rock has been found in the quartz 
monzonite. The deposits are concentrated in two northwest- 
bearing trends, and they are both stratigraphically and struc- 
turally controlled and are usually manto shaped. 



29 



Two-thirds of the known resources in the district occur 
in the Upper Guilmette. Zinc, copper, lead, and silver-bearing 
minerals occur in the sedimentary deposits, but the ratios vary 
widely depending on horizon. The additional potential 
resources for the entire area are probably much larger than 
the demonstrated resources. Both of the Nevada sites oc- 
cur in NMVT deposits. 



NEW JERSEY 

The Sterling Mine occurs in a district that consists largely 
of a series of Precambrian metasediments and metavolcanics 
intruded by a number of silicic igneous rocks (26). The 
sediments have been complexly folded and are synclinal in 
form. Minerals occur in certain limestone beds of the Franklin 
marble as NMVT replacement deposits. Mineralized rock may 
also occur in contact with pegmatite dikes elsewhere in the 
district. The mineral assemblage of the area is extremely 
unusual, and the major minerals are franklinite and willemite 
with minor zincite. 



NEW MEXICO 

The Pinos Altos deposit is located in the Silver City Min- 
ing District, an area that produced zinc, lead, copper, and 
gold in the past. Paleozoic and Cretaceous sedimentary rocks 
form a structural uplift that is cut by numerous igneous in- 
trusives. the most important of which is the Pinos Altos quartz 
monzonite stock. 

Most of the minerals occur in altered silty limestones and 
calcareous siltstones in the Pennsylvanian Syrena and 
Oswaldo Formations of the Magdalena Group. The NMVT 
deposit consists mainly of stratabound skarn replacement 
bodies in a kidney-shaped pattern, which trend in a north- 
easterly direction. Copper is dominant in the northern part 
of the deposit while lead, zinc, and silver are prominent in 
the southern part of the deposit. 



NEW YORK 

The Balmat and Pierrepont Mines are located in or near 
the Balmat-Edwards District, from which lead and zinc were 
first produced in the early 1900's. The district is located on 
a complex synformal structure, with lead and zinc minerals 
occurring in a zone that trends northeast-southwest. The 
NMVT stratiform deposits occur within certain marble and 
dolomite horizons of the metasedimentary Grenville Series. 
Minerals have been concentrated in the noses of folds and 
are generally conformable to the bedding. 

Similar carbonate units and structures occur throughout 
the central part of the Adirondack lowlands (28). Hence, con- 
ditions are very favorable for the discovery of additional zinc 
sulfide deposits in the northwest Adirondacks. 



PENNSYLVANIA 

The Friedensville Mine is located in a small, folded and 
down-faulted block of early Paleozoic sediments of the Great 
Valley Province, which are surrounded by rocks of the New 
England crystalline uplift. Sphalerite occurs in gray crystalline 
dolomite in the lower portion of the Beekmantown Formation. 
The MVT mineralization is stratabound and occurs mainly as 
cementation in breccia bodies, but some replacement of ad- 
jacent strata also occurs. 



TENNESSEE AND KENTUCKY 

All of the deposits in Tennessee and Kentucky, with the 



exception of the Copperhill mines, are MVT deposits and oc- 
cur in dolomite or limestone beds in either the Kingsport For- 
mation and/or the Mascot Dolomite of the CambroOrdovician 
Knox Group. 

The deposits evaluated occur in either the central 
Tennessee-Kentucky area, the Copper Ridge District, or the 
Mascot-Jefferson City District. Strata are generally horizon- 
tal in the central Tennessee-Kentucky region but dip 
moderately to the southeast in the other two districts. The 
mines ana deposits evaluated for the Tennessee and Ken- 
tucky area are listed in table C-1 and their locations are shown 
on figure C-2. 

The minerals generally occur in breccia bodies that are 
very complex and irregular in shape, forming a netlike pat- 
tern around islands of barren rock. Individual breccia bodies 



Table C-1 . — Primary zinc operations in Tennessee and Kentucky 

Map 
number' 

Central Tennessee Zinc Region: 

Hartsville Area 1 

Hartsville 2 

Fountain Run 3 

Carthage Property 4 

Cumberland Property 5 

Gordonsville-Elmwood 6 

Stonewall 7 

Gainesboro ! 8 

Right Fork 9 

East Gainesboro 10 

Roaring River 11 

Cub Creek 12 

Cumberland 13 

Cumberland Deposit 14 

Burkesville Project 15 

Pall Mall 16 

Copperhill 17 

Mascot-Jefferson City Zinc District: 

Immel 18 

Beaver Creek 19 

Young 20 

New Market 21 

Zinc Mine 22 

Jefferson City Mine 23 

Lost Creek 24 

Coy 25 

Copper Ridge District: 

Idol 26 

Big War Creek 27 

1 Locations on figure C-2. 




COWUL »io« district] 
t 2* r 



FIGURE C-2.— Locations of zinc operations in Tennessee 
and Kentucky. 



30 



located on different stratigraphic levels may be connected 
by vertical pipe-shaped breccia bodies (breakthrough ore 
bodiesjialso containing mineralized rock. All of the deposits 
are MVT with sphalerite as the major zinc mineral. Cadmium 
is also recovered at the producing operations (21). 

The Copperhill mines are located in the Ducktown Min- 
ing District of Tennessee. For this investigation, the Boyd, 
Calloway, Cherokee, and Eureka Mines and the North and 
South Pits were combined and evaluated as 'Copperhill' 
because they would all utilize the Copperhill mill. Minerals 
occur in metamorphosed massive sulfide accumulations in 
metamorphosed interbedded graywackes and mica schists 
in the Late Precambrian Copperhill Formation of the Great 
Smoky Group. These rocks have been folded and faulted. 
There are two or possibly three series of beds that are 
favorable for mineralization, and many of the deposits occur 
where the favorable sediments have been thickened by 
folding. The Copperhill mines are in NMVT deposits. 

The minable ore deposits of the Ducktown area can be 
assigned to three general groups: northwestern, south- 
eastern, and central. The Calloway Mine belongs to the 
southeastern group, while the Eureka, Boyd, and Cherokee 
Mines belong to the central group. The ore bodies of the first 
two groups are high in copper and zinc, while those of the 
central group are higher in sulfur and iron. All the deposits 
contain iron, copper, and zinc, with minor gold, silver, and 
galena (26). 



UTAH 

The Ontario Mine is located in the Park City Mining 
District. The district is developed in an area of approximately 
100 sq km on a northward-plunging anticline and syncline 
of Paleozoic and Mesozoic sediments. Intrusive and extrusive 
igneous rocks are also present throughout the district and 
were important to the deposition and control of mineraliza- 
tion. The ore bodies occur as both bedded replacement and 
vein deposits, of which the replacement deposits have the 
highest lead and zinc content. The district only contains 
NMVT deposits. 

Current interest centers around the replacement 
deposits, which occur most often in limestone beds of the 
Paleozoic Humbug, Doughnut, Deseret, Weber, Park City, 
and the Mesozoic Thaynes Formations. The ore bodies at 
the Ontario Mine occur most frequently in the Humbug For- 
mation, to a lesser extent in the Doughnut and Deseret For- 
mations, and consist of zinc, lead, and silver-bearing 
minerals. 

On a district-wide scale, most of the individual ore bodies 
are quite small, and many of the mines intersect numerous 
ore bodies. Ore type is not uniform throughout the district. 
"The silver-rich ores are far more commonly developed in 
the northern part of the district, while those rich in gold and 
copper occur in the lower reaches of the fissure systems to 
the south" (26). These metals add significant value to the 
lead-zinc ore. Mineralization at the Ontario Mine falls between 
these two extremes. 



WASHINGTON 

The Washington Zinc Unit, formerly known as the Van 



Stone Mine, and the Metaline District lie within the southern 
portion of the Kootenay arc, a narrow belt of folds and faults 
extending southwest from British Columbia into Washington. 
The MVT deposits occur as both concordant and discordant 
mineralized bodies in the Middle Cambrian Metaline 
Limestone. Minerals occur in the middle dolomite unit of the 
Metaline limestone at the Washington Zinc Unit mine and in 
the Josephine horizon in the Metaline District. 

The deposits of the Metaline District occur within a 
graben block of about 120 sq km in size. Although the replace- 
ment deposits occur throughout the graben area, a greater 
number of them occur in the southern portion of the district. 
The known resources for the entire Metaline District were 
evaluated. 

The deposits are generally found in silicified brecciated 
dolomite, in the axes of folds, and in highly fractured zones. 
The deposits are very irregularly shaped but are generally 
conformable to the bedding. Individual ore bodies range in 
size from a few to several hundred meters in length and width. 



WISCONSIN 

The Shullsburg, Bearhole, Elmo No. 3, and Crawhall 
Mines are located in the Upper Mississippi Valley Zinc-Lead 
District. The district encompasses about 6,400 sq km, 
predominantly in southwestern Wisconsin. Most of the past 
production has come from the Platteville-Galena-Shullsburg 
area. Minerals occur in several different horizons of the 
Paleozoic sedimentary rocks, the most important of which 
are the Middle Ordovician Decorah, Galena, and Platteville 
Formations. Most of the lead production has come from the 
Galena. 

These four sites all occur in MVT deposits, where the 
majority of the minerals occur in fractures and open spaces. 
Ore bodies that are more disseminated in character occur 
in the northern part of the district, while vein deposits are more 
common in the southern part of the district. Mineralized 
bodies are separated from each other by large sections of 
barren rock. Mineralized ratios change with locale, and zinc, 
lead, or barite may each be the dominant mineral of a par- 
ticular deposit. 

The Crandon and Pelican River massive sulfide deposits 
occur in a belt of metamorphosed Precambrian volcanic rocks 
that strike east-west across Wisconsin. Recent exploration 
has been concentrated in a 100-km-wide greenstone belt 
stretching about 350 km from Ladysmith to Pembine (29). The 
Flambeau-Ladysmith copper deposit also occurs in this belt. 

Both the Crandon and Pelican River deposits'are NMVT 
deposits that are Precambrian stockworks, with minerals oc- 
curring in a series of closely spaced stringers. The Crandon 
deposit has two entirely distinct ore types: stringer ore, which 
contains copper with minor zinc, and massive sulfide ore, 
which contains zinc-copper-lead mineralization. Both ore 
types occur separately and will also be mined and treated 
separately. In addition, small amounts of gold and silver 
occur. 

Further exploration in the greenstone belt could yield 
substantial additional resources of copper, lead, or zinc. The 
lack of nearby smelting and refining capacity has hampered 
development, and exploration and development work has 
been difficult in recent years owing to the environmental 
climate in the State. 



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